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1. Change this post color to yellow.
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3. When was he born? When did he die?
4. Give short summary of the astronomer's life
5. What are other notable discoveries did this astronomer make?

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Was born in 276 BC – and died in 194 BC.
Eratosthenes was a librarian, geographer, mathematician, astronomer, historian, and poet, among other things. Pentathlos, or athlete who competes in five different events, was his nickname. The name seemed appropriate for a scholar who excelled in a variety of subjects. Although most of Eratosthenes' works have been lost, his work and results have been documented by other researchers.
He was one of the first people to use the word Geography. Invented a system of longitude and latitude invented a system of longitude and latitude. Also made a map of the known world. Invented a system to find prime numbers. x

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1643 - 1727

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Discovery: What was their contribution to our understanding of the universe?

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Discovery: What was their contribution to our understanding of the universe?

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1. Change this post to green.
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3. What did he observe? How did he figure it out?
4. What tools did he use?
5. What does it mean to our understanding of the universe (at that time)?

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1. Change this post to purple.
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3. Who or what idea did he get his inspiration from for his discovery? What are his connections to history, in the past or future?

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Add a separate posts, add some resources you found interesting about the astronomer.

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Born - February 15, 1564
Died - January 8, 1642
Education - University of Pisa

Galileo was an Italian astronomer, Physicist and Engineer from the city of Pisa.  He discovered that the moon's surface wasn't smooth and had crater and mountains, the first pendulum clock, the phases of Venus, Jupiters moons and many more...

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He created the theory that the universe is constantly expanding, he also witnessed the first poison attack in WWI.

During his life he came up with a theory similar to the big bang theory but not exactly there yet called the "cosmic egg" which consisted of a single compressed atom that burst open causing the universe to exist.

I think he died right after WWII.

(I think he came up with the script for the movie "A Talking Cat!?!" before he died.)

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-Johannes Kepler was born on December 27, 1571 in Württemberg, Germany. He died on November 15, 1630, in Regensburg, Germany.
-During Kepler's childhood, his parents were very poor and Kepler was often really sick. However, his evident intelligence earned him a scholarship to the University of Tübingen to study for the Lutheran ministry. Throughout Kepler's life, people thought that planets orbited in perfect circles. Kepler not only adamantly defended the idea that planets orbit the sun, but also that planets don't orbit in perfect circles.
-Kepler discovered 3 major laws of planetary motion. These are that the planets move in elliptical orbits with the Sun at one focus; the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central body and that arc (the “area law”), and there is an exact relationship between the squares of the planets’ periodic times and the cubes of the radii of their orbits (the “harmonic law”).

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(born c. 310 BCE—died c. 230 BCE) greek astronomer who maintained that earth rotates on its axis and revolves around the Sun. On this ground, the Greek philosopher cleanthes the stoic declared in his Against Aristarchus that Aristarchus ought to be indicted for impiety “for putting into motion the hearth of the universe.”

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1868 - 1921, she did the science and discovered how to measure stellar distances.

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Her work helped American astronomer Edwin Hubble measure galaxy distances in the 1920s, which led to his realization that the universe is expanding.

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Discovery: What was their contribution to our understanding of the universe?

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Discovery: What was their contribution to our understanding of the universe?

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She discovered that some of these stars have a consistent brightness no matter where they are located, making these so-called Cepheid variables a good measuring stick for astronomical distances.

Henrietta Swan Leavitt was a Harvard "computer" — one of several women in the early 1900s who studied photographic plates for fundamental properties of stars. Leavitt is best known for discovering about 2,400 variable stars.

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- born 18 February 1201, Died 26 June 1274
- Nasir al-Din al-Tusi was born in Tus, in northwest Iran (near Nishapur) in 1201
- Nasir al-Din al-Tusi was an Islamic astronomer and mathematician who joined the Mongols who conquered Baghdad. He made important contributions to astronomy and wrote many commentaries on Greek texts.

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Edwin Hubble was born on November 20th, 1889 and died on September 28th, 1953.

He was the third son of Virginia James and John Hubble, who was a lawyer and insurance sales man. As a student, Hubble earned good grades, but he was more excelling as an athlete. At the university of Chicago, he studied astronomy, mathematics and philosophy. Hubble graduated with a bachelor of science and spent 3 years on his master's as one of Oxford University's first Rhodes scholars. Throughout those years his love and interest for astronomy never lessened.

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Born on February 19, 1473.
Died on May 24, 1543
Copernicus's father died when he was young. His uncle wanted him to study the laws, but he spend most of the time studying astronomy and mathematics. In 1514 he wrote a book, which set out the view of the universe. He never married, but he had relationships with his housekeeper

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What was their contribution to understanding the universe?

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What was their contribution to understanding the universe?

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Discovered the distance from the earth to moon/sun. At the time, he calculated the most accurate circumference of the earth. Eratosthenes built a pole at Alexandria and observed that it formed a shadow on the summer solstice, proving that the Sun was not directly overhead but slightly south. Eratosthenes was able to calculate the planet's circumference by identifying the curvature of the Earth and knowing the distance between the two towns.
At the time, it was a huge step toward understanding the solar system, and it was one of the things that a lot of studies were based on.

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Discovery: What was their contribution to our understanding of the universe?

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Discovery: What was their contribution to our understanding of the universe?

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Nicolas Copernicus found out that the center of the Earth is not the center of the Universe, only of Earth’s gravity and of the lunar sphere. The Sun is fixed and all other spheres revolve around the Sun. (Copernicus retained the idea of spheres and of perfectly circular orbits. In fact, the orbits are elliptical, which the German astronomer Johannes Kepler demonstrated in 1609.) Earth has more than one motion, turning on its axis and moving in a spherical orbit around the sun. The stars are fixed but appear to move because of the Earth’s motion. By 1532 Copernicus had mostly completed a detailed astronomical manuscript he had been working on for 16 years. He had resisted publishing it for fear of the ensuing controversy and out of hope for more data. Finally, in 1541, the 68-year-old Copernicus agreed to publication, supported by a mathematician friend, Georg Rheticus, a professor at the University of Wittenberg, in Germany. How long did it take for Copernicus’s ideas to reach the general public? Does anyone nowadays still believe the apparent evidence before their eyes that the Sun moves around the Earth to set and rise? Almost everyone learns in childhood that, despite appearances, the Earth moves around the Sun.

Copernicus’s model asked people to give up thinking that they lived in the center of the Universe. For him the thought of the Sun illuminating all of the planets as they rotated around it had a sense of great beauty and simplicity.

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https://www.space.com/15684-nicolaus-copernicus.html
https://www.khanacademy.org/humanities/big-history-project/big-bang/how-did-big-bang-change/a/nicolaus-copernicus-bh?modal=1

He met the famous astronomer Domenico Maria Novara da Ferrara and became his disciple and assistant. Copernicus was developing new ideas inspired by reading the "Epitome of the Almagest" (Epitome in Almagestum Ptolemei) by George von Peuerbach and Johannes Regiomontanus (Venice, 1496).

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Nicolaus Copernicus proposed his theory that the revolved around in the 1500s, when most people believed that Earth was the center of the universe. Although his model wasn't completely correct, it formed a strong foundation for future scientists, such as Galileo, to build on and improve humanity's understanding of the motion of heavenly bodies.

Indeed, other astronomers built on Copernicus' work and proved that our planet is just one world orbiting one star in a vast cosmos loaded with both, and that we're far from the center of anything.
Countdown: The most famous astronomers of all time
Born on Feb. 19, 1473, in Toruń, Poland, Mikolaj Kopernik (Copernicus is the Latinized form of his name) traveled to to attend college, according to the Encyclopedia Britannica. Copernicus' father had died when the child was young, and his uncle became a leading figure in his life.

Copernicus' uncle wanted him to study the laws and regulations of the Catholic Church then return home to become a canon, a type of official in the Catholic Church.

However, while visiting several academic institutions, Copernicus spent most of his time studying mathematics and . While attending the University of Bologna, Copernicus lived and worked with astronomy professor Domenico Maria de Novara, doing research and helping him make observations of the heavens.

Due to his uncle's influence, Copernicus did become a canon in Warmia, in northern Poland, although he never took orders as a priest. He conducted his astronomical research in between his duties as canon, the Encyclopedia Britannica noted.

(Image credit: Public domain)

The Copernican model of the solar system

In Copernicus' lifetime, most believed that Earth held its place at the center of the universe. The sun, the , and all of the planets revolved around it.

One of the glaring mathematical problems with this model was that the planets, on occasion, would travel backward across the sky over several nights of observation. Astronomers called this retrograde motion. To account for it, the current model, based on the Greek astronomer and mathematician view, incorporated a number of circles within circles - epicycles - inside of a planet's path. Some planets required as many as seven circles, creating a cumbersome model many felt was too complicated to have naturally occurred.

In 1514, Copernicus distributed a handwritten book to his friends that set out his view of the universe. In it, he proposed that the center of the universe was not Earth, but that the sun lay near it. He also suggested that Earth's rotation accounted for the rise and setting of the sun, the movement of the stars, and that the cycle of seasons was caused by Earth's revolutions around it.

Finally, he (correctly) proposed that Earth's motion through space caused the retrograde motion of the planets across the night sky (planets sometimes move in the same directions as stars, slowly across the sky from night to night, but sometimes they move in the opposite, or retrograde, direction).

Copernicus finished the first manuscript of his book, "De Revolutionibus Orbium Coelestium" ("On the Revolutions of the Heavenly Spheres") in 1532. In it, Copernicus established that the planets orbited the sun rather than the Earth. He laid out his model of the solar system and the path of the planets.

He didn't publish the book, however, until 1543, just two months before he died. He diplomatically dedicated the book to Pope Paul III. The church did not immediately condemn the book as heretical, perhaps because the printer added a note that said even though the book's theory was unusual, if it helped astronomers with their calculations, it didn't matter if it wasn't really true. It probably also helped that the subject was so difficult that only highly educated people could understand it. The Church did eventually ban the book in 1616, according to Physics Today.

The Catholic Church wasn't the only Christian faith to reject Copernicus' idea.

"When 'De Revolutionibus Orbium Coelestium' was published in 1543, religious leader Martin Luther voiced his opposition to the heliocentric solar system model," says Biography.com. "His underling, Lutheran minister Andreas Osiander, quickly followed suit, saying of Copernicus, 'This fool wants to turn the whole art of astronomy upside down.'"

Copernicus died on May 24, 1543, of a stroke. He was 70.

(Image credit: Getty/Moment)

Where was Copernicus buried?

In 2008, researchers announced that a skull found in Frombork Cathedral did belong to the astronomer, according to The Guardian. By matching DNA from the skull to hairs found in books once owned by Copernicus, the scientists confirmed the identity of the astronomer. Polish police then used the skull to reconstruct how its owner might have looked.

Nature quotes the AFP as stating that the reconstruction "bore a striking resemblance to portraits of the young Copernicus."

In 2010, his remains were blessed with holy water by some of Poland's highest-ranking clerics before being reburied, his grave marked with a black granite tombstone decorated with a model of the solar system. The tomb marks both his scientific contribution and his service as church canon.

"Today's funeral has symbolic value in that it is a gesture of reconciliation between science and faith," Jacek Jezierski, a local bishop who encouraged the search for Copernicus, said according to the Associated Press. "Science and faith can be reconciled."

The unmarked grave was not linked to suspicions of heresy, as his ideas were only just being discussed and had yet to be forcefully condemned, according to Jack Repcheck, author of " C opernicus' Secret: How the Scientific Revolution Began."

"Why was he just buried along with everyone else, like every other canon in Frombork?" Repcheck said. "Because at the time of his death he was just any other canon in Frombork. He was not the iconic hero that he has become."

(Image credit: iStock / Getty Images Plus)

Refining the work of Copernicus

Although Copernicus' model changed the layout of the universe, it still had its faults. For one thing, Copernicus held to the classical idea that the planets traveled in perfect circles. It wasn't until the 1600s that Johannes Kepler proposed the orbits were instead ellipses. As such, Copernicus' model featured the same epicycles that marred Ptolemy's work, although there were fewer.

Copernicus' ideas took nearly a hundred years to seriously take hold. When Galileo Galilei claimed in 1632 that Earth orbited the sun, building upon the Polish astronomer's work, he found himself under house arrest for committing heresy against the Catholic Church.

Despite this, the observations of the universe proved the two men correct in their understanding of the motion of celestial bodies. Today, we call the model of the solar system, in which the planets orbit the sun, a heliocentric or Copernican model.

"Sometimes Copernicus is honored as having substituted the old geocentric system with the new, heliocentric one, as having regarded the sun, instead of the Earth, as the unmoving center of the universe," Konrad Rudnicki, an astronomer and author of " The Cosmological Principles," wrote. "This view, while quite correct, does not render the actual significance of Copernicus's work."

According to Rudnicki, Copernicus went beyond simply creating a model of the solar system.

"All his work involved a new cosmological principle originated by him. It is today called the Genuine Copernican Cosmological Principle and says, 'The Universe as observed from any planet looks much the same,'" Rudnicki wrote.

So while Copernicus' model physically placed the sun at the center of the solar system, it also figuratively removed the focus from Earth, making it just another planet.

Additional resources

You can read the English translation of Copernicus' manuscript "De Revolutionibus Orbium Cœlestium" here. Check out the complete works of Nicholas Copernicus Complete in " On the Revolutions: Nicholas Copernicus Complete Works (Foundations of Natural History)". Also, discover the many artefacts at the British Museum regarding Nicolaus Copernicus, here.

Bibliography

Jack Repcheck, " Copernicus' Secret: How the Scientific Revolution Began," Simon & Schuster, 2008.

Sheila Rabin, " Nicolaus Copernicus," The Stanford Encyclopedia of Philosophy, 2019.

Fred Hoyle, "The work of Nicolaus Copernicus," Proceedings of the Royal Society A, Volume 336, January 1974, https://doi.org/10.1098/rspa.1974.0009.

Teresa Zielinska, "Nicolaus Copernicus (1473-1543)," Distinguished Figures in Mechanism and Machine Science, History of Mechanism and Machine Science Volume 1, 2007, https://doi.org/10.1007/978-1-4020-6366-4_5

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Nicolaus Copernicus Biography: Facts & Discoveries

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Nicolaus Copernicus proposed his theory that the revolved around in the 1500s, when most people believed that Earth was the center of the universe . Although his model wasn't completely correct, it formed a strong foundation for future scientists, such as Galileo, to build on and improve humanity's understanding of the motion of heavenly bodies.

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Galileo Galilei heard of the telescope in 1609. He wanted to learn more about it, so by trail and error he was able to improve the spy glass in the lenses. With this telescope he was able to recreate the moon and discover the moon's surface is not smooth instead it's rough and uneven. In January 1619 he discovered the 4 moons revolving over Jupiter and the ring surrounding Saturn. After a few more planet discoveries he came with the conclusion that the sun is the center of the universe.

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-was born on 22 March 1394
-died on 27 October 1449
Ulug`beg was the grandson of the conqueror Tamerlane and was a mathematician and astronomer. He founded an important centre for study at Samarkand staffed with the best scientists of the time. He did important early work on trigonometry.

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https://mathshistory.st-andrews.ac.uk/Biographies/Copernicus/

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Quick Info

Born

19 February 1473
Toruń, Poland

Died

24 May 1543
Frauenburg (now Frombork), Poland

Summary

Copernicus was a Polish astronomer and mathematician whose theory that the Earth moved around the Sun profoundly altered later workers' view of the universe, but was rejected by the Catholic church.

Biography

Nicolaus Copernicus is the Latin version of the famous astronomer's name which he chose later in his life. The original form of his name was Mikolaj Kopernik or Nicolaus Koppernigk but we shall use Copernicus throughout this article. His father, also called Nicolaus Koppernigk, had lived in Kraków before moving to Toruń where he set up a business trading in copper. He was also interested in local politics and became a civic leader in Toruń and a magistrate. Nicolaus Koppernigk married Barbara Watzenrode, who came from a well off family from Toruń, in about 1463. They moved into a house in St Anne's Street in Toruń, but they also had a summer residence with vineyards out of town. Nicolaus and Barbara Koppernigk had four children, two sons and two daughters, of whom Nicolaus Copernicus was the youngest.

You can see a picture of the house in which Copernicus was born at THIS LINK.

When young Nicolaus was ten years old his father died. His uncle Lucas Watzenrode, who was a canon at Frauenburg Cathedral, became guardian to Nicolaus and Barbara Koppernigk's four children.

You can see a picture of Lucas Watzenrode at THIS LINK.

Nicolaus and his brother Andreas remained in Toruń, continuing their elementary education there. In 1488 Nicolaus was sent by his uncle to the cathedral school of Włocławek where he received a good standard humanist education. After three years of study at Włocławek he entered the University of Kraków (situated in what was then the capital of Poland). By this time Lucas Watzenrode was Bishop of Ermland and he envisaged a church career for both of his nephews. Andreas, Nicolaus's brother, entered the University of Kraków at the same time, and both their names appear on the matriculation records of 1491-92.

University education at Kraków was, Copernicus later wrote, a vital factor in everything that he went on to achieve. There he studied Latin, mathematics, astronomy, geography and philosophy. He learnt his astronomy from Tractatus de Sphaera by Johannes de Sacrobosco written in 1220. One should not think, however, that the astronomy courses which Copernicus studied were scientific courses in the modern sense. Rather they were mathematics courses which introduced Aristotle and Ptolemy's view of the universe so that students could understand the calendar, calculate the dates of holy days, and also have skills that would enable those who would follow a more practical profession to navigate at sea. Also taught as a major part of astronomy was what today we would call astrology, teaching students to calculate horoscopes of people from the exact time of their birth.

While a student in Kraków, Copernicus purchased a copy of the Latin translation of Euclid's Elements published in Venice in 1482, a copy of the second edition of the Alfonsine Tables (which gives planetary theory and eclipses) printed in Venice in 1492, and Regiomontanus's Tables of Directions (a work on spherical astronomy) published in Augsburg in 1490. Remarkably Copernicus's copies of these works, signed by him, are still preserved.

It was while he was a student at Kraków that Copernicus began to use this Latin version of his name rather than Kopernik or Koppernigk. He returned to Toruń after four years of study at Kraków but, as was common at the time, did not formally graduate with a degree. His uncle Lucas Watzenrode was still determined that Copernicus should have a career in the Church and indeed this was a profession which would allow security for someone wanting to pursue leaning. So that he might have the necessary qualifications Copernicus decided to go to the University of Bologna to take a degree in canon law. In the autumn of 1496 he travelled to Italy, entering the University of Bologna on 19 October 1496, to start three years of study. As a native German speaker he joined the "German Nation of Bologna University". Each student contributed to the "German Nation" an amount they could afford and the small contribution that Copernicus made indicates his poor financial position at that time.

While he was there his uncle put his name forward for the position of canon at Frauenburg Cathedral. On 20 October 1497, while in Bologna, Copernicus received official notification of his appointment as a canon and of the comfortable income he would receive without having to return to carry out any duties. At Bologna University Copernicus studied Greek, mathematics and astronomy in addition to his official course of canon law. He rented rooms at the house of the astronomy professor Domenico Maria de Novara and began to undertake research with him, assisting him in making observations. On 9 March 1497 he observed the Moon eclipse the star Aldebaran.

In 1500 Copernicus visited Rome, as all Christians were strongly encouraged to do to celebrate the great jubilee, and he stayed there for a year lecturing to scholars on mathematics and astronomy. While in Rome he observed an eclipse of the Moon which took place on 6 November 1500. He returned to Frauenburg (also known as Frombork) in the spring of 1501 and was officially installed as a canon of the Ermland Chapter on 27 July. He had not completed his degree in canon law at Bologna so he requested his uncle that he be allowed to return to Italy both to take a law degree and to study medicine. Copernicus was granted leave on 27 July 1501 :-

... principally because Nicolaus promised to study medicine, and as a helpful physician would some day advise our most reverend bishop and also the members of the Chapter.
As this quotation indicates, the Cathedral Chapter liked his proposal to study medicine and provided the necessary funds. He set off again for Italy, his time going to Padua. Copernicus had another reason to return to Italy, which he almost certainly did not disclose, and that was to continue his studies of astronomy.

Padua was famous for its medical school and while he was there Copernicus studied both medicine and astronomy. At that time astronomy was essentially astrology and, as such, considered relevant to medicine since physicians made use of astrology. In the spring of 1503 he decided formally to obtain his doctorate in Canon Law, but he did not return to Bologna but rather took the degree at the University of Ferrara. After receiving his doctorate, Copernicus stayed in Ferrara for a few months before returning to Padua to continue his studies of medicine. There is no record that he ever graduated from Padua.

When he returned to his native land, Copernicus was again granted leave from his official duties as a canon in the Ermland Chapter at Frauenburg. This was allow him to be physician to his maternal uncle Lucas Watzenrode, the Bishop of Ermland, but he carried out far more duties for his uncle than medical ones becoming essentially his private secretary and personal advisor. For about five years he undertook these duties and during this period he lived at Heilsberg Castle, a few miles from Frauenburg, the official residence of the Bishop of Ermland.

In 1509 Copernicus published a work, which was properly printed, giving Latin translations of Greek poetry by the obscure poet Theophylactus Simocattes. While accompanying his uncle on a visit to Kraków, he gave a manuscript of the poetry book to a publisher friend there. Lucas Watzenrode died in 1512 and following this Copernicus resumed his duties as canon in the Ermland Chapter at Frauenburg. He now had more time than before to devote to his study of astronomy, having an observatory in the rooms in which he lived in one of the towers in the town's fortifications.

You can see a picture of Copernicus's observatory in Frauenburg at THIS LINK.

Around 1514 he distributed a little book, not printed but hand written, to a few of his friends who knew that he was the author even though no author is named on the title page. This book, usually called the Little Commentary, set out Copernicus's theory of a universe with the sun at its centre. The Little Commentary is a fascinating document. It contains seven axioms which Copernicus gives, not in the sense that they are self evident, but in the sense that he will base his conclusions on these axioms and nothing else; see . What are the axioms? Let us state them:

1. There is no one centre in the universe.

2. The Earth's centre is not the centre of the universe.

3. The centre of the universe is near the sun.

4. The distance from the Earth to the sun is imperceptible compared with the distance to the stars.

5. The rotation of the Earth accounts for the apparent daily rotation of the stars.

6. The apparent annual cycle of movements of the sun is caused by the Earth revolving round it.

7. The apparent retrograde motion of the planets is caused by the motion of the Earth from which one observes.

Some have noted that 2, 4, 5, and 7 can be deduced from 3 and 6 but it was never Copernicus's aim to give a minimal set of axioms. The most remarkable of the axioms is 7, for although earlier scholars had claimed that the Earth moved, some claiming that it revolved round the sun, nobody before Copernicus appears to have correctly explained the retrograde motion of the outer planets. Even when he wrote his Little Commentary Copernicus was planning to write a major work, for he wrote in it (see ):-
Here, for the sake of brevity, I have thought it desirable to omit the mathematical demonstrations intended for my larger work.
It is likely that he wrote the Little Commentary in 1514 and began writing his major work De revolutionibus in the following year.

Given Copernicus's nature it is clear that he would have liked to have lived a quiet life at Frauenburg, carrying out his (relatively few) duties conscientiously and devoting all his spare time to observing, developing his theories of the universe, and writing De revolutionibus . It is equally clear that his fame as an astronomer was well known for when the Fifth Lateran Council decided to improve the calendar, which was known to be out of phase with the seasons, the Pope appealed to experts for advice in 1514, one of these experts was Copernicus. Many experts went to Rome to advise the Council, but Copernicus chose to respond by letter. He did not wish to contribute more to the discussions on the calendar since he felt that the motions of the heavenly bodies was still not understood with sufficient precision.

The peace which Copernicus wished, however, was not easy to find in a period of frequent wars. The fortifications of Frauenburg that formed Copernicus's home had been built to protect the town which had been captured by various opposing groups over the years. In 1516 Copernicus was given the task of administering the districts of Allenstein (also known as Olsztyn) and Mehlsack. He lived for four years in Allenstein Castle while carrying out these administrative duties.

You can see a picture of Allenstein Castle where Copernicus lived at THIS LINK.

Always keen to make observations, Copernicus returned to his home/observatory in Frauenburg whenever there was a reason to attend a meeting or consult with the other canons, always taking the opportunity to further his researches. However when war broke out between Poland and the Teutonic Knights towards the end of 1519 Copernicus was back in Frauenburg. After a period of war, Copernicus was sent to participate in peace talks in Braunsberg as one of a two man delegation representing the Bishop of Ermland. The peace talks failed and the war continued. Frauenburg came under siege but Copernicus continued making his observations even at this desperate time. By the autumn of 1520 Copernicus was back living in Allenstein Castle and had to organise its defence against attacking forces. The castle resisted the attack and by 1521 an uneasy peace had returned.

As a reward for his defence of Allenstein, Copernicus was appointed Commissar of Ermland and given the task of rebuilding the district after the war. His close friend, Tiedemann Giese, another canon in the Chapter, was given the task of assisting him.

You can see a picture of Tiedemann Giese at THIS LINK.

As part of the recovery plan, Copernicus put forward a scheme for the reform of the currency which he presented to the Diet of Graudenz in 1522. However, despite attending the Diet and arguing strongly for his sensible proposals, they were not acted on.

Copernicus returned to Frauenburg where his life became less eventful and he had the peace and quiet that he longed for to allow him to make observations and to work on details of his heliocentric theory. Having said that he now had the peace he wanted, one should also realise that he was undertaking his mathematical and astronomical work in isolation with no colleagues with whom to discuss matters. Although Copernicus was a canon, he had never become a priest. In fact on 4 February 1531 his bishop threatened to take away his income if he did not enter the priesthood, yet Copernicus still refused.

A full account of Copernicus's theory was apparently slow to reach a state in which he wished to see it published, and this did not happen until the very end of Copernicus's life when he published his life's work under the title De revolutionibus orbium coelestium (Nuremberg, 1543). In fact had it not been for Georg Joachim Rheticus, a young professor of mathematics and astronomy at the University of Wittenberg, Copernicus's masterpiece might never have been published. In May 1539 Rheticus arrived at Frauenburg where he spent about two years with Copernicus. Rheticus wrote of his visit:-
I heard of the fame of Master Nicolaus Copernicus in the northern lands, and although the University of Wittenberg had made me a Public Professor in those arts, nonetheless, I did not think that I should be content until I had learned something more through the instruction of that man. And I also say that I regret neither the financial expenses nor the long journey nor the remaining hardships. Yet, it seems to me that there came a great reward for these troubles, namely that I, a rather daring young man, compelled this venerable man to share his ideas sooner in this discipline with the whole world.
We should note that Rheticus was a Protestant, so in those troubled times of the Reformation he took somewhat of a risk visiting a Catholic stronghold. In September 1539 Rheticus went to Danzig, visiting the mayor of Danzig, who gave him some financial assistance to help publish the Narratio Prima or, to give it its full title First report to Johann Schöner on the Books of the Revolutions of the learned gentleman and distinguished mathematician, the Reverend Doctor Nicolaus Copernicus of Toruń, Canon of Warmia, by a certain youth devoted to mathematics. The publication of this work encouraged Copernicus to publish the full mathematical details of his theory which he had promised 27 years earlier. Swerdlow writes:-
Copernicus could not have asked for a more erudite, elegant, and enthusiastic introduction of his new astronomy to the world of good letters; indeed to this day the "Narratio Prima" remains the best introduction to Copernicus's work.
In his First Report Rheticus wrote about Copernicus's way of working (see ):-
... my teacher always had before his eyes the observations of all ages together with his own, assembled in order as in catalogues; then when some conclusion must be drawn or contribution made to the science and its principles, he proceeds from the earliest observations to his own, seeking the mutual relationship which harmonizes them all; the results thus obtained by correct inference under the guidance of Urania he then compares with the hypothesis of Ptolemy and the ancients; and having made a most careful examination of these hypotheses, he finds that astronomical proof requires their rejection; he assumes new hypotheses, not indeed without divine inspiration and the favour of the gods; by applying mathematics, he geometrically establishes the conclusions which can be drawn from them by correct inference; he then harmonizes the ancient observations and his own with the hypotheses which he has adopted; and after performing all these operations he finally writes down the laws of astronomy ...
While living with Copernicus, Rheticus wrote to several people reporting on the progress Copernicus was making. For example on 2 June 1541 Rheticus wrote that Copernicus :-
... is enjoying quite good health and is writing a great deal ...
while he wrote that on 9 June Copernicus :-
... had finally overcome his prolonged reluctance to release his volume for publication.
By 29 August De revolutionibus orbium coelestium was ready for the printer. Rheticus took the manuscript with him when he returned to his teaching duties at Wittenberg, and gave it the printer Johann Petreius in Nürnberg. This was a leading centre for printing and Petreius was the best printer in town. However, since he was unable to stay to supervise the printing he asked Andreas Osiander, a Lutheran theologian with considerable experience of printing mathematical texts, to undertake the task. What Osiander did was to write a letter to the reader, inserted in place of Copernicus's original Preface following the title page, in which he claimed that the results of the book were not intended as the truth, rather that they merely presented a simpler way to calculate the positions of the heavenly bodies. The letter was unsigned and the true author of the letter was not revealed publicly until Kepler did so 50 years later. Osiander also subtly changed the title to make it appear less like a claim of the real world. Some are appalled at this gigantic piece of deception by Osiander, as Rheticus was at the time, others feel that it was only because of Osiander's Preface that Copernicus's work was read and not immediately condemned.

In De revolutionibus Copernicus states several reasons why it is logical that the sun would be at the centre of the universe:-
At the middle of all things lies the sun. As the location of this luminary in the cosmos, that most beautiful temple, would there be any other place or any better place than the centre, from which it can light up everything at the same time? Hence the sun is not inappropriately called by some the lamp of the universe, by others its mind, and by others its ruler.
Copernicus's cosmology placed a motionless sun not at the centre of the universe, but close to the centre, and also involved giving several distinct motions to the Earth. The problem that Copernicus faced was that he assumed all motion was circular so, like Ptolemy, was forced into using epicycles (see for example ). It was consequently considered implausible by the most of his contemporaries, and by most astronomers and natural philosophers until the middle of the seventeenth century. In the intended Preface of De revolutionibus orbium coelestium Copernicus showed that he was fully aware of the criticisms that his work would attract:-
Perhaps there will be babblers who, although completely ignorant of mathematics, nevertheless take it upon themselves to pass judgement on mathematical questions and, badly distorting some passages of Scripture to their purpose, will dare find fault with my undertaking and censure it. I disregard them even to the extent as despising their criticism as unfounded.
Its notable defenders included Kepler and Galileo while theoretical evidence for the Copernican theory was provided by Newton's theory of universal gravitation around 150 years later.

Copernicus is said to have received a copy of the printed book, consisting of about 200 pages written in Latin, for the first time on his deathbed. He died of a cerebral haemorrhage.

Brahe, who did not accept Copernicus's claim that the Earth moved round the sun, nevertheless wrote:-
Through observations made by himself [Copernicus] discovered certain gaps in Ptolemy, and he concluded that the hypotheses established by Ptolemy admit something unsuitable in violation of the axioms of mathematics. Moreover, he found the Alfonsine computations in disagreement with the motions of the heavens. Therefore, with wonderful intellectual acumen he established different hypotheses. He restored the science of the heavenly motions in such a way that nobody before him had a more accurate knowledge of the movements of the heavenly bodies.
Rudnicki gives this appreciation of Copernicus:-
He was truly creative. His scientific method, though determined by the horizons of contemporary knowledge and belief, was yet ideally objective. Ethically, his actions throughout his life bear witness to the highest standards. He did good. He earned the general respect and honour of his contemporaries. For many years he served self-sacrificingly the cause of his native country. But he knew no private, domestic joys.

Written by J J O'Connor and E F Robertson
Last Update November 2002

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Born 19 February 1473 Toruń, Poland Died 24 May 1543 Frauenburg (now Frombork), Poland Summary Copernicus was a Polish astronomer and mathematician whose theory that the Earth moved around the Sun profoundly altered later workers' view of the universe, but was rejected by the Catholic church.

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Galileo was initially interested in maths. He taught mathematics to university students. His love for astronomy began to form when he began his studies on motion which he pursued steadily for the next two decades.
Galileo Galilei provided a number of scientific insights that laid the foundation for future scientists. His investigation of the laws of motion and improvements on the telescope helped further the understanding of the world and universe around him.

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Galileo Galilei: Father of Modern Science

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Discovery: What was their contribution to our understanding of the universe?

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Discovery: What was their contribution to our understanding of the universe?

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-Using the observations from Brahe, Kepler found that the orbits of the planets followed three laws.
-Brahe's observations were used with a Tyconian Quadrant which Brahe made himself and was widely copied. The Tyconian Quadrant measures the coordinates of astronomical objects according to their position on the quadrant and the time at which the astronomical objects hit an indicator on the mural quadrant. This data gave Kepler sufficient evidence to create the 3 planetary laws of motion.
- kepler's discoveries greatly impacted the understanding of the universe at the time as his discoveries proved all the myths about planetary motion and the universe wrong. He proved that planets move around the sun in ellipses, not circles (as had been widely believed at that time), and that planets speed up as they approach the sun and slow down as they move away.

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Mirzo Ulugbeks observatory in Samarkand 

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Mirzo Ulugbek calculated with unprecedented accuracy the stellar year length, 365 days, 6 hours, 10 minutes, 8 seconds, and the error was less than a minute.
He determined the inclination of the Earth’s axis. During his lifetime, the scientific works of Ulugbek were known all over the world. Chinese wrote and talked about him and used the astronomical calculations of Ulugbek. After 200 years, the British scientists were engaged in the discoveries of Ulugbek. His scientific works were translated into Latin.

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Contribution to the Knowledge about Universe

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Contribution to the Knowledge about Universe

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He discovered a star known as the Capheid Variable, the rate the stars move through a certain cycle; it offers to help finding how far away the star is. He found this by using a telescope, paying attention and observing the movement in the Nebulae to find new stars. This kept going, until he realized the the Andromeda Nebulae was actually a universe. Before this discovery scientists thought that the Milky Way and the Universe were the same thing, but this proved that the universe was much greater than just milky way.

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Isaac Newton was born in Woolsthorpe, Lincolnshire, England on Christmas Day. His father had died three months earlier, and baby Isaac, very premature, was also not expected to survive. But he overcame it and grew up as a very smart student, eventually attending Cambridge University. The university closed, and Newton returned home, where he spent two years concentrating on problems in mathematics and physics. This is when he figured out the principles of gravity. He went on to make some amazing feats, like his infamous 3 laws of motion. His mother supposedly wanted him to be a farmer.

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https://www.britannica.com/biography/Galileo-Galilei/Galileos-Copernicanism

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He was a very smart man who was very curious about many things, and his main inspiration was to find out about the most he could throughout his life. His connections in history is that he participated in many events, such as measuring earth, writing books and poems and creating a library in Alexandria.

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http://galileoandeinstein.phys.virginia.edu/lectures/gkastr1.html
https://www.famousscientists.org/eratosthenes/
https://www.khanacademy.org/humanities/big-history-project/solar-system-and-earth/knowing-solar-system-earth/a/eratosthenes-of-cyrene

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In this lecture, we shall show how the Greeks made the first real measurements of astronomical distances: the size of the earth and the distance to the moon, both determined quite accurately, and the distance to the sun, where their best estimate fell short by a factor of two.

How big is the Earth?

The first reasonably good measurement of the earth's size was done by Eratosthenes, a Greek who lived in Alexandria, Egypt, in the third century B.C. He knew that far to the south, in the town of Syene (present-day Aswan, where there is now a huge dam on the Nile) there was a deep well and at midday on June 21, the sunlight reflected off the water far down in this well, something that happened on no other day of the year. The point was that the sun was exactly vertically overhead at that time, and at no other time in the year. Eratosthenes also knew that the sun was never vertically overhead in Alexandria, the closest it got was on June 21, when it was off by an angle he found to be about 7.2 degrees, by measuring the shadow of a vertical stick.

The distance from Alexandria to Syene was measured at 5,000 stades (a stade being 500 feet), almost exactly due south. From this, and the difference in the angle of sunlight at midday on June 21, Eratosthenes was able to figure out how far it would be to go completely around the earth.

Of course, Eratosthenes fully recognized that the Earth is spherical in shape, and that "vertically downwards" anywhere on the surface just means the direction towards the center from that point. Thus two vertical sticks, one at Alexandria and one at Syene, were not really parallel. On the other hand, the rays of sunlight falling at the two places were parallel. Therefore, if the sun's rays were parallel to a vertical stick at Syene (so it had no shadow) the angle they made with the stick at Alexandria was the same as how far around the Earth, in degrees, Alexandria was from Syene.

According to the Greek historian Cleomedes, Eratosthenes measured the angle between the sunlight and the stick at midday in midsummer in Alexandria to be 7.2 degrees, or one-fiftieth of a complete circle. It is evident on drawing a picture of this that this is the same angle as that between Alexandria and Syene as seen from the center of the earth, so the distance between them, the 5,000 stades, must be one-fiftieth of the distance around the earth, which is therefore equal to 250,000 stades, about 23,300 miles. The correct answer is about 25,000 miles, and in fact Eratosthenes may have been closer than we have stated here---we're not quite sure how far a stade was, and some scholars claim it was about 520 feet, which would put him even closer.

How High is the Moon?

How do we begin to measure the distance from the earth to the moon? One obvious thought is to measure the angle to the moon from two cities far apart at the same time, and construct a similar triangle, like Thales measuring the distance of the ship at sea. Unfortunately, the angle difference from two points a few hundred miles apart was too small to be measurable by the techniques in use at the time, so that method wouldn't work.

Nevertheless, Greek astronomers, beginning with Aristarchus of Samos (310-230 B.C., approximately) came up with a clever method of finding the moon's distance, by careful observation of a lunar eclipse, which happens when the earth shields the moon from the sun's light.

For a short movie illustrating a lunar eclipse, click here!

To better visualize a lunar eclipse, just imagine holding up a quarter (diameter one inch approximately) at the distance where it just blocks out the sun's rays from one eye. Of course you shouldn't try this---you'll damage your eye! You can try it with the full moon, which happens to be the same apparent size in the sky as the sun. It turns out that the right distance is about nine feet away, or 108 inches. If the quarter is further away than that, it is not big enough to block out all the sunlight. If it is closer than 108 inches, it will totally block the sunlight from some small circular area, which gradually increases in size moving towards the quarter. Thus the part of space where the sunlight is totally blocked is conical, like a long slowly tapering icecream cone, with the point 108 inches behind the quarter. Of course, this is surrounded by a fuzzier area, called the "penumbra", where the sunlight is partially blocked. The fully shaded area is called the "umbra". (This is Latin for shadow. Umbrella means little shadow in Italian.) If you tape a quarter to the end of a thin stick, and hold it in the sun appropriately, you can see these different shadow areas.

Question: If you used a dime instead of a quarter, how far from your eye would you have to hold it to just block the full moonlight from that eye? How do the different distances relate to the relative sizes of the dime and the quarter? Draw a diagram showing the two conical shadows.

Now imagine you're out in space, some distance from the earth, looking at the earth's shadow. (Of course, you could only really see it if you shot out a cloud of tiny particles and watched which of them glistened in the sunlight, and which were in the dark.) Clearly, the earth's shadow must be conical, just like that from the quarter. And it must also be similar to the quarter's in the technical sense---it must be 108 earth diameters long! That is because the point of the cone is the furthest point at which the earth can block all the sunlight, and the ratio of that distance to the diameter is determined by the angular size of the sun being blocked. This means the cone is 108 earth diameters long, the far point 864,000 miles from earth.

Now, during a total lunar eclipse the moon moves into this cone of darkness. Even when the moon is completely inside the shadow, it can still be dimly seen, because of light scattered by the earth's atmosphere. By observing the moon carefully during the eclipse, and seeing how the earth's shadow fell on it, the Greeks found that the diameter of the earth's conical shadow at the distance of the moon was about two-and-a-half times the moon's own diameter.

Note: It is possible to check this estimate either from a photograph of the moon entering the earth's shadow, or, better, by actual observation of a lunar eclipse.
Question: At this point the Greeks knew the size of the earth (approximately a sphere 8,000 miles in diameter) and therefore the size of the earth's conical shadow (length 108 times 8,000 miles). They knew that when the moon passed through the shadow, the shadow diameter at that distance was two and a half times the moon's diameter. Was that enough information to figure out how far away the moon was?
Well, it did tell them the moon was no further away than 108x8,000 = 864,000 miles, otherwise the moon wouldn't pass through the earth's shadow at all! But from what we've said so far, it could be a tiny moon almost 864,000 miles away, passing through that last bit of shadow near the point. However, such a tiny moon could never cause a solar eclipse. In fact, as the Greeks well knew, the moon is the same apparent size in the sky as the sun. This is the crucial extra fact they used to nail down the moon's distance from earth.

They solved the problem using geometry, constructing the figure above. In this figure, the fact that the moon and the sun have the same apparent size in the sky means that the angle ECD is the same as the angle EAF. Notice now that the length FE is the diameter of the earth's shadow at the distance of the moon, and the length ED is the diameter of the moon. The Greeks found by observation of the lunar eclipse that the ratio of FE to ED was 2.5 to 1, so looking at the similar isosceles triangles FAE and DCE, we deduce that AE is 2.5 times as long as EC, from which AC is 3.5 times as long as EC. But they knew that AC must be 108 earth diameters in length, and taking the earth's diameter to be 8,000 miles, the furthest point of the conical shadow, A, is 864,000 miles from earth. From the above argument, this is 3.5 times further away than the moon is, so the distance to the moon is 864,000/3.5 miles, about 240,000 miles. This is within a few percent of the right figure. The biggest source of error is likely the estimate of the ratio of the moon's size to that of the earth's shadow as it passes through.

How far away is the Sun?

This was an even more difficult question the Greek astronomers asked themselves, and they didn't do so well. They did come up with a very ingenious method to measure the sun's distance, but it proved too demanding in that they could not measure the important angle accurately enough. Still, they did learn from this approach that the sun was much further away than the moon, and consequently, since it has the same apparent size, it must be much bigger than either the moon or the earth.

Their idea for measuring the sun's distance was very simple in principle. They knew, of course, that the moon shone by reflecting the sun's light. Therefore, they reasoned, when the moon appears to be exactly half full, the line from the moon to the sun must be exactly perpendicular to the line from the moon to the observer (see the figure to convince yourself of this). So, if an observer on earth, on observing a half moon in daylight, measures carefully the angle between the direction of the moon and the direction of the sun, the angle a in the figure, he should be able to construct a long thin triangle, with its baseline the earth-moon line, having an angle of 90 degrees at one end and a at the other, and so find the ratio of the sun's distance to the moon's distance.

The problem with this approach is that the angle a turns out to differ from 90 degrees by about a sixth of a degree, too small to measure accurately. The first attempt was by Aristarchus, who estimated the angle to be 3 degrees. This would put the sun only five million miles away. However, it would already suggest the sun to be much larger than the earth. It was probably this realization that led Aristarchus to suggest that the sun, rather than the earth, was at the center of the universe. The best later Greek attempts found the sun's distance to be about half the correct value (92 million miles).

The presentation here is similar to that in Eric Rogers, Physics for the Inquiring Mind, Princeton, 1960.

Some exercises related to this material are presented in my notes for Physics 621.

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In this lecture, we shall show how the Greeks made the first real measurements of astronomical distances: the size of the earth and the distance to the moon, both determined quite accurately, and the distance to the sun, where their best estimate fell short by a factor of two.

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Some stellar achievements(no pun intended) made by this absolute legend
- Discovery of Newton's law of universal gravitation

- Newton's acceleration law F=ma, where F=Force, m= mass and a= acceleration

- Newton's 3 laws of motion

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https://www.famousscientists.org/edwin-hubble/

Hubble was helped by Henrietta Leavitt's discovery about a star known as Cepheid variable and the rate at which the star goes through a dim-bright-dim cycle that offers a way to find out how far it is.

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Lived 1889 - 1953.
Edwin Hubble's work produced a dramatic change in people's beliefs about the universe, proving it is home to galaxies besides the Milky Way.

Hubble showed we live in a universe of many galaxies separated by immense distances, each an isolated 'island universe.' Just as Copernicus caused an epochal change when he removed Earth from the center of the solar system, Hubble did so too when he removed our galaxy from the center of the universe.

Hubble's Law signals that the farther away another galaxy is, the faster it is moving away from us. Most scientists believe this means we live in an expanding universe, although Hubble was reluctant to accept this interpretation without further experimental proof.

Beginnings

Edwin Powell Hubble was born on November 20, 1889 in the township of Marshfield, Missouri, USA.

His mother was Virginia Lee James. His father was John Powell Hubble, who had a law degree and was an insurance salesman. Edwin was the third of eight children, not all of whom survived childhood.

The Hubble family were financially prosperous. They needed to be mobile because of John Hubble's insurance career, and they lived in the suburbs of cities including Chicago and Louisville. Their homes were large and prestigious and staffed with servants.

The Hubble children were all given chores to do, because their parents believed this helped them develop better characters.

Edwin began reading when he was an infant, trying to keep up with his elder brother and sister who had started school. His favorite books were adventure stores by Jules Verne and H. Rider Haggard.

When he was seven, his grandfather, who was an enthusiastic amateur astronomer, showed him one of his telescopes. Edwin was so eager to use it that he asked if he could stay up at night studying the heavens rather than have an eighth birthday party.

High School

Edwin seems to have sailed easily through his studies at Wheaton High School near Chicago. His grades in English, Mathematics, Biology, Chemistry, Physics, Latin, and German were usually between 95 and 100. He actually spent more time on sports than study. Encouraged by his father, he worked as a delivery boy during his vacations. He graduated from high school in 1906, age 16, with a scholarship for the University of Chicago.

College

In the fall of 1906, still 16, Hubble enrolled at Chicago. He continued devoting a great deal of time to sport, particularly basketball, athletics, and heavyweight boxing. Records show that on May 6, 1906 he set a new state record for the high jump, clearing 5 feet 8-and-a-half inches. Hubble was six foot two inches tall and strongly built. In 1910, he graduated with a Bachelor's of Science degree, with credits in sciences including physics and astronomy.

Hubble spent the next three years on the other side of the Atlantic at the University of Oxford on a Rhodes scholarship. He was still enthusiastic about science, particularly astronomy, but he studied Jurisprudence (the theory of law) in deference to his law-graduate father. Hubble graduated with a Bachelor of Arts in 1912. He spent a further year learning Spanish. During his time at Oxford, he spent two summer vacations cycling around Europe, but thoughts about his future direction were never far from his mind, and he was thinking big. He wrote his mother:

In the fall of 1912, Hubble learned that his father was dying. He asked his father's permission to leave Oxford and return to see him. His father refused, telling his son to keep working. His father died in January 1913.

Teaching and Graduate School

Hubble returned to the USA in the summer of 1913.

He got a job teaching Spanish and Physics at New Albany High School, Indiana. He also coached the school basketball team and did commercial German translation work. He was a very popular teacher, but he did not enjoy it much.

He contacted Forest Ray Moulton, an astronomy professor at the University of Chicago, asking about graduate work. Moulton wrote Edwin Frost, head of the university's Yerkes Observatory in Wisconsin, saying Hubble:

And so, age 24, Hubble finally entered the field that had fascinated him since he first looked through his grandfather's telescope almost two decades earlier. He began a Ph.D. in Astronomy, graduating in 1917 with the thesis Photographic Investigations of Faint Nebulae.

World War 1 then intervened and Hubble spent a year in the army and a year at the University of Cambridge carrying out astronomy research work.

In 1919, age 30, he began work at Mount Wilson Observatory in California, renowned for its clear air and excellent viewing conditions. He would remain there for the rest of his life.

Edwin Hubble's Contributions to Science

Galaxies Beyond Our Own

Hubble studied nebulae for his Ph.D. and he returned to this work at Mount Wilson, where he could make observations using the world's largest telescope, the 100-inch (2.5 m) Hooker Telescope.

In 1912, Henrietta Leavitt had discovered something remarkable about a type of star known as a Cepheid variable: the rate at which this type of star goes through a dim-bright-dim cycle is highly significant; it offers a way of finding out how far away the star is.

In the early 1920s, benefitting from access to the huge Hooker Telescope, Hubble found Cepheid variable stars located in nebulae. He paid close attention to the Andromeda nebula, and discovered that the Cepheid variables within the nebula are at tremendous distances from the earth, much farther than stars in our own Milky Way galaxy.

Hubble realized that the Andromeda nebula is actually a galaxy. Until then, most astronomers thought the Milky Way and the universe were the same thing. Hubble now knew that the universe was considerably bigger than the Milky Way, it contained other galaxies or 'island universes.'

Hubble found:

His best photographs of the outer parts of the Andromeda and Triangulum nebulae showed "dense swarms of actual stars."

Many of the stars were Cepheid variables.

The nebulae were located almost a million light-years † from Earth - four times farther away than anything observed before.

The Andromeda nebula's diameter exceeded 30,000 light-years††, making it bigger than the Milky Way.

The Andromeda galaxy emitted light of the order of a billion of our suns.

Three days after his thirty-fifth birthday, Hubble's discovery was announced - not in a scientific journal - but in The New York Times. His results had actually been circulating quietly among America's astronomers for some time: the official presentation came in a paper he submitted to be read at the January 1, 1925 meeting of the American Astronomical Society.

Hubble had changed our view of the universe forever. Our own vast galaxy, home to our sun and 100 billion other stars, is but one of billions of other galaxies.

In addition to this, Hubble gave us the system we use for classifying galaxies, shown below:

Red Shift is Directly Related to Distance

The eminent astronomer Vesto Slipher had also studied nebulae. In 1913, he had reported that light from nebulae was shifted to the red end of the spectrum.

He interpreted his discovery as a Doppler shift, one of the most familiar examples of which is the pitch of a police car's siren: if the car is racing towards you the pitch is raised; if it is racing away from you the pitch is lowered.

Light behaves in a similar way. Light emitted by an object racing away from Earth is shifted to the red end of the spectrum.

Slipher examined a number of nebulae - he did not know they were galaxies - and found light from a large majority of them showed a significant red shift, indicating they were moving away from Earth at prodigious speeds.

In 1929, Hubble took Slipher's red-shift data and combined it with red-shift observations he and his assistant Milton Humason had made. He plotted the red-shift data against galaxy distance data and found a remarkable correlation.

Hubble turned the relationship from his graph into an equation, now called Hubble's Law, which says:

where v is velocity, r is distance, and H is the Hubble Constant, which Hubble calculated to be 530 km s⁻¹ Mpc⁻¹. Today, with the benefit of much more sophisticated observational data and better distance calibrations, H is believed to be approximately 70 km s⁻¹ Mpc⁻¹.

The Expanding Universe

One interpretation of Hubble's Law is that we live in an expanding universe. Hubble did not believe there was enough hard evidence to support this interpretation of red-shifts.

In fact, although Hubble brought the scientific world's attention to Hubble's Law, the law was in fact discovered two years earlier by Georges Lemaître. Unfortunately for Lemaître, his work received little attention. Lemaître calculated H to be 625 km s⁻¹ Mpc⁻¹.

Not only did Lemaître discover 'Hubble's Law,' his interpretation of it is the one accepted by modern cosmologists. Lemaître used Albert Einstein's theory of general relativity to show that red-shifts would result naturally if the very fabric of space itself were expanding.

However, Hubble's point of view was perfectly logical. Although the existence of 'dark matter' in the universe often seems a modern concern, Hubble wrote that the red-shifts could only be justified as evidence for an expanding universe if the density of matter in the universe were much larger than had actually been observed. He said the density of matter needed to accept red-shifts as evidence of an expanding universe is:

Also, if Hubble, for the sake of argument, accepted that red-shifts were caused by an expanding universe, observational data led him to believe that the universe's rate of expansion was slowing.

The Expanding Universe - Very Tricky

As an illustration of just how tricky this field is, in 2011, Saul Perlmutter, Brian Schmidt and Adam Riess shared the Nobel Prize in Physics "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae."

However, in 2016, a joint report by physicists at the Niels Bohr Institute and University of Oxford said that an analysis of more data than used by the Nobel winners indicated that the evidence for an accelerating expansion fell short of that required for a discovery of fundamental significance.

No doubt an unchallenged picture of what our universe is doing and why it is doing it will emerge, but it might be some time yet.

Honors

Hubble received a large number of awards in his lifetime, including the Newcomb Cleveland Prize in 1924; the Bruce Medal in 1938; the Franklin Medal in 1939; and the Gold Medal of the Royal Astronomical Society in 1940. For his work in World War 2, when he was chief of ballistics and director of the supersonic wind tunnel laboratory at Aberdeen, Maryland, he was awarded the Legion of Merit in 1946.

Probably the greatest honor Hubble received, albeit posthumously, was the naming of the great space telescope for him. The Hubble Space Telescope has transformed cosmology, provided images of unmatched beauty, and yielded data that has driven both a better understanding of the universe and an ongoing realization that we do not know or understand everything yet.

Some Personal Details and the End

In February 1924, age 34, Hubble married Grace Burke Leib, a graduate of Stanford University. They had no children.

Hubble's main hobby was book collecting - particularly books relating to the history of science. He became a trustee of the Huntington Library in San Marino.

Curiously, for a man who achieved greatness, Hubble gained a reputation for eccentricities. As a young man, he left America as an all-American college graduate and returned from Oxford as a pipe-smoking English gentleman, complete with whimsical turns of phrase that even Bertie Wooster might have hesitated to use. Hubble also became prone to exaggerating some of the experiences of his earlier years, such as his sporting achievements.

Hubble's discovery of other galaxies made him famous. He featured on the front page of Time magazine in 1948, and he and Grace became close friends with the novelist Aldous Huxley and his wife Maria, and met many of Hollywood's stars.

In 1949, age 59, Hubble suffered a serious heart attack. He was nursed back to health by Grace, but had to reduce his working hours - no more long cold nights at the telescope were allowed.

Edwin Hubble died, age 63, of a stroke (cerebral thrombosis) on September 28, 1953 in San Marino, California. At his own request, his final resting place is not known and Grace destroyed his personal papers. When Grace died in 1980 she was buried in the same secret resting place.

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Further Reading
Edwin Hubble
The Realm of the Nebulae
Yale University Press, 1936

Edwin Hubble
The Observational Approach to Cosmology
Oxford Clarendon, 1937

W. S. Adams
Obituary: Dr. Edwin P. Hubble
The Observatory, Vol. 74, pp. 32-35, 1954

R. Berendzen and M. Hoskin
Hubble's Announcement of Cepheids in Spiral Nebulae
Astronomical Society of the Pacific Leaflets, Vol. 10, No. 504, pp. 425-440, 1967

Donald E. Osterbrock, Ronald S. Brashear, Joel A. Gwinn
Self-Made Cosmologist: The Education of Edwin Hubble
ASP Conference Series, Vol. 10, Evolution of the Universe of Galaxies; Proceedings of the Edwin Hubble Centennial Symposium, ed. by Richard G. Kron, pp. 1-18

Alexander S. Sharov, Igor D. Novikov
Edwin Hubble, The Discoverer of the Big Bang Universe
Cambridge University Press, 1993

William H. Cropper
Great Physicists: The Life and Times of Leading Physicists from Galileo to Hawking
Oxford University Press, 2004

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Lived 1889 - 1953. Edwin Hubble's work produced a dramatic change in people's beliefs about the universe, proving it is home to galaxies besides the Milky Way. Hubble showed we live in a universe of many galaxies separated by immense distances, each an isolated 'island universe.'

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- Kepler got his inspiration from his Math professor who was also an astronomer, Michael Maestlin, who encouraged his interest and was an early believer of Kepler's idea even though most didn't agree. After mentoring and motivating Kepler towards his discovery, Maestlin was one of the first astronomers able to observe the 1604 Supernova.

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https://www.britannica.com/biography/Johannes-Kepler

https://learnodo-newtonic.com/johannes-kepler-contributions

https://www.space.com/15787-johannes-kepler.html

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Johannes Kepler (1571 - 1630) was a German mathematician and astronomer who was a key figure of the Scientific Revolution. His most famous accomplishment are his three laws of planetary motion which laid the foundation of celestial mechanics. Kepler discovered that planets move in elliptical orbits and at different speeds at different times, according to their distance from the sun. Apart from his contributions to astronomy, Kepler laid the foundation of modern optics. Among other things, he formulated the inverse-square law governing the intensity of light; invented an improved refracting telescope; and correctly explained the working of a human eye. As founder of celestial mechanics and optics, Johannes Kepler is considered one of the most influential scientists in history. Know more about his accomplishments in astronomy, optics and other fields of physics through his 10 major contributions.

#1 He was the first to publish a defense of the heliocentric model of Copernicus

The first major astronomical work of Johannes Kepler, Mysterium Cosmographicum (The Cosmographic Mystery) was published in 1596. The work primarily tried to justify the six known planets and their distances from the sun in terms of the five Platonic solids. Mysterium was the first ever published defense of the Copernican system. Though Copernicus proposed a heliocentric model in his renowned work "De Revolutionibus orbium coelestium", he resorted to Ptolemaic devices in order to explain the change in planets' orbital speed, and also continued to use as a point of reference the center of the earth's orbit rather than that of the sun. Mysterium, despite the flaw of its main thesis, is considered an important work in astronomy as it got rid of the remaining defects of the Ptolemaic theory from the Copernican system.

#2 He discovered that a planet moved at different speeds according to its distance from the sun

Using the accurate astronomical and planetary observations of Danish astronomer Tycho Brahe, Johannes Kepler analyzed the orbit of Mars and discovered that Mars didn't move in a perfect circle around the sun, as was believed at the time. He found that it was closer to the sun at certain times than at others. Furthermore, it moved faster when it was farther away. Kepler supposed that the motive power radiated by the Sun weakens with distance, causing faster or slower motion as planets move closer or farther from it. In 1602, Kepler deduced what came to be known as his second law: the speed of the planet changes at each moment such that the time between two positions is always proportional to the area swept out on the orbit between these positions.

#3 Johannes Kepler discovered that planets move in elliptical orbits around the sun

After formulating his second law of planetary motion, Kepler set about calculating the entire orbit of Mars, using the geometrical rate law and assuming an egg-shaped ovoid orbit. In 1605, after around 40 failed attempts, Kepler ultimately found that Mars follows an elliptical path around the sun, an idea he had assumed to be too simple a solution for earlier astronomers to have overlooked. Kepler thus arrived at his first law of planetary motion: that the planets orbit the sun in ellipses, with the sun at one focus. It is interesting to note that Kepler discovered the second law before the first.

#4 His work Astronomia nova is considered one of the most important books in astronomy

Kepler published his ten-year-long investigation of the motion of Mars in his most renowned work Astronomia nova (New Astronomy). Apart from including the first two of the three principles known today as Kepler's laws of planetary motion, it provided strong arguments for heliocentrism. The idea that a planet moved in an elliptical orbit with its speed varying according to its distance from the Sun was completely revolutionary at the time. Kepler also discussed an attractive virtue of earth, similar to magnetism. He considered this attraction as mutual and proportional to the bulk of the bodies. But, he considered gravity to have a limited range and did not know how this force varied with distance. Kepler's idea thus differed significantly from Newton's later concept of gravitation. Astronomia nova was a highly influential work of the scientific revolution and it is considered as one of the most significant books in the history of astronomy.

#5 He discovered his third law of planetary motion while writing Harmonices Mundi

Published in 1619, Harmonices Mundi (The Harmony of the World) is a book by Johannes Kepler in which he attempts to find harmony in nature by explaining proportions of the natural world in terms of music. The Harmony of the World is explained in five chapters on: regular polygons; the congruence of figures; music; astrology; and the motions of the planets. Among the harmonies in the book is the third law of planetary motion: that the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit. It was years later, in the 1660s, that the importance of this law was realized by scientists when it was combined with the newly discovered law of centrifugal force. The Harmony also contains the earliest mathematical understanding of two types of regular star polyhedra known as Kepler's solids, the small stellated dodecahedron and the great stellated dodecahedron.

#6 His book Epitome became a highly influential work in astronomy

Epitome Astronomiae Copernicanae (Epitome of Copernican Astronomy) is an influential book by Kepler which was published in three volumes in 1617, 1620 and 1621. The Epitome contained all three laws of planetary motion and attempted to explain heavenly motions through physical causes. It extended the first two laws of planetary motion, which he had previously applied only to Mars, to all the planets as well as the Moon and satellites of Jupiter. Kepler's laws of planetary motion are part of the foundation of modern astronomy and physics. The Epitome thus had a huge impact on future scientists and is considered one of his most important works. Also, the term "inertia" was introduced for the first time in this book. Kepler defined it only in terms of a resistance to movement and thus it was not exactly the same as its modern interpretation.

#7 He laid the foundation of modern optics

Johannes Kepler began his investigation of the laws of optics in 1600, and in 1604, his work Astronomiae Pars Optica (The Optical Part of Astronomy) was published. Among other things, the book contains Kepler's formulation of the law that the intensity of light decreases with the square of distance; description of reflection by flat and curved mirrors; and astronomical implications of optics such as parallax, astronomical refraction and the apparent sizes of heavenly bodies. Astronomiae Pars Optica is considered as the foundation of modern optics. Another influential work in optics by Kepler, Dioptrice, was published in 1611. Among other things, it contained the concepts of real vs. virtual images; upright vs. inverted images; and the effects of focal length on magnification and reduction.

#8 Kepler was the first to correctly explain the working of a human eye

Camera obscura is the natural optical phenomenon in which light rays reverse themselves when they pass through a small aperture resulting in an inverted image on the screen opposite to the opening. It is the principle on which the pinhole camera works. Johannes Kepler was the first to use the term "camera obscura" in his 1604 work Astronomiae Pars Optica; and to discover that it was the principle behind the working of the pinhole camera. Kepler extended his study to the human eye and recognized that an image is reversed by the eye's lens; and is formed on the retina; and that it is inverted. Thus Kepler laid the foundation for the field of ophthalmologic optics. His discovery later helped explain physical phenomena like central visual acuity, visual field, dark adaptation and errors of refraction.

#9 He invented the Keplerian telescope, an improved refracting telescope

In his 1604 work Astronomiae Pars Optica, Kepler put forward the first correct explanation as to why convex and concave lenses could correct presbyopia and myopia. Then, in his 1611 work Dioptrice, Kepler set out the theoretical basis of double-convex converging lenses and double-concave diverging lenses; and explained how they combined to produce a Galilean telescope. He went on to describe an improved refracting telescope which would use two convex lenses to produce higher magnification than Galileo's combination of convex and concave lenses. Keplerian telescope could achieve considerably higher magnifications than Galilean telescope.

#10 Johannes Kepler was a key figure of the scientific revolution

In 1627, Johannes Kepler published his Rudolphine Tables, a star catalog and planetary tables based on the observations of Tycho Brahe. For most stars these tables were accurate to within one arc minute, a significant achievement at that time. Rudolphine Tables was the first catalog to include corrective factors for atmospheric refraction; and is considered the best of the pre-telescop ic catalogs. Kepler's novel, titled Somnium (The Dream), was published posthumously in 1634. It described a fantastic trip to the moon; and what lunar astronomy would be like. Famous writer Isaac Asimov referred to Somnium as the first work of science fiction. As founder of celestial mechanics and optics, Johannes Kepler was a key figure of the Scientific Revolution, an age which saw the intellectual transformation of Europe. He laid the foundation for future scientists like Isaac Newton; and is considered among the most influential figures in the history of science.

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Johannes Kepler's 10 Major Contributions To Science

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Johannes Kepler (1571 - 1630) was a German mathematician and astronomer who was a key figure of the Scientific Revolution. His most famous accomplishment are his three laws of planetary motion which laid the foundation of celestial mechanics. Kepler discovered that planets move in elliptical orbits and at different speeds at different times, according to their distance from the sun.

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Isaac Newton was inspired to discover newton's law of universal gravitation by an apple. Newton believed that the power that cause apple to fall was gravity. Reason that the apple fell was because gravity was the force that existed between all objects in the universe.

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This legendary figure, among other things, established the laws of universal gravitation. Almost all of modern astronomical science is based on his law that "every particle attracts every other particle in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers."  The law, when put in mathematical form, looks like this:

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Equation of Newton's law of universal gravitation

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Equation of Newton's law of universal gravitation

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just for reference

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https://www.khanacademy.org/humanities/big-history-project/big-bang/how-did-big-bang-change/a/isaac-newton

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READ: Isaac Newton (article) | The Big Bang | Khan Academy

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Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

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https://www.famousscientists.org/edwin-hubble/

https://www.khanacademy.org/humanities/big-history-project/big-bang/how-did-big-bang-change/a/edwin-hubble?modal=1

http://btc.montana.edu/ceres/html/Universe/unibackground.htm

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Lived 1889 - 1953.
Edwin Hubble's work produced a dramatic change in people's beliefs about the universe, proving it is home to galaxies besides the Milky Way.

Hubble showed we live in a universe of many galaxies separated by immense distances, each an isolated 'island universe.' Just as Copernicus caused an epochal change when he removed Earth from the center of the solar system, Hubble did so too when he removed our galaxy from the center of the universe.

Hubble's Law signals that the farther away another galaxy is, the faster it is moving away from us. Most scientists believe this means we live in an expanding universe, although Hubble was reluctant to accept this interpretation without further experimental proof.

Beginnings

Edwin Powell Hubble was born on November 20, 1889 in the township of Marshfield, Missouri, USA.

His mother was Virginia Lee James. His father was John Powell Hubble, who had a law degree and was an insurance salesman. Edwin was the third of eight children, not all of whom survived childhood.

The Hubble family were financially prosperous. They needed to be mobile because of John Hubble's insurance career, and they lived in the suburbs of cities including Chicago and Louisville. Their homes were large and prestigious and staffed with servants.

The Hubble children were all given chores to do, because their parents believed this helped them develop better characters.

Edwin began reading when he was an infant, trying to keep up with his elder brother and sister who had started school. His favorite books were adventure stores by Jules Verne and H. Rider Haggard.

When he was seven, his grandfather, who was an enthusiastic amateur astronomer, showed him one of his telescopes. Edwin was so eager to use it that he asked if he could stay up at night studying the heavens rather than have an eighth birthday party.

High School

Edwin seems to have sailed easily through his studies at Wheaton High School near Chicago. His grades in English, Mathematics, Biology, Chemistry, Physics, Latin, and German were usually between 95 and 100. He actually spent more time on sports than study. Encouraged by his father, he worked as a delivery boy during his vacations. He graduated from high school in 1906, age 16, with a scholarship for the University of Chicago.

College

In the fall of 1906, still 16, Hubble enrolled at Chicago. He continued devoting a great deal of time to sport, particularly basketball, athletics, and heavyweight boxing. Records show that on May 6, 1906 he set a new state record for the high jump, clearing 5 feet 8-and-a-half inches. Hubble was six foot two inches tall and strongly built. In 1910, he graduated with a Bachelor's of Science degree, with credits in sciences including physics and astronomy.

Hubble spent the next three years on the other side of the Atlantic at the University of Oxford on a Rhodes scholarship. He was still enthusiastic about science, particularly astronomy, but he studied Jurisprudence (the theory of law) in deference to his law-graduate father. Hubble graduated with a Bachelor of Arts in 1912. He spent a further year learning Spanish. During his time at Oxford, he spent two summer vacations cycling around Europe, but thoughts about his future direction were never far from his mind, and he was thinking big. He wrote his mother:

In the fall of 1912, Hubble learned that his father was dying. He asked his father's permission to leave Oxford and return to see him. His father refused, telling his son to keep working. His father died in January 1913.

Teaching and Graduate School

Hubble returned to the USA in the summer of 1913.

He got a job teaching Spanish and Physics at New Albany High School, Indiana. He also coached the school basketball team and did commercial German translation work. He was a very popular teacher, but he did not enjoy it much.

He contacted Forest Ray Moulton, an astronomy professor at the University of Chicago, asking about graduate work. Moulton wrote Edwin Frost, head of the university's Yerkes Observatory in Wisconsin, saying Hubble:

And so, age 24, Hubble finally entered the field that had fascinated him since he first looked through his grandfather's telescope almost two decades earlier. He began a Ph.D. in Astronomy, graduating in 1917 with the thesis Photographic Investigations of Faint Nebulae.

World War 1 then intervened and Hubble spent a year in the army and a year at the University of Cambridge carrying out astronomy research work.

In 1919, age 30, he began work at Mount Wilson Observatory in California, renowned for its clear air and excellent viewing conditions. He would remain there for the rest of his life.

Edwin Hubble's Contributions to Science

Galaxies Beyond Our Own

Hubble studied nebulae for his Ph.D. and he returned to this work at Mount Wilson, where he could make observations using the world's largest telescope, the 100-inch (2.5 m) Hooker Telescope.

In 1912, Henrietta Leavitt had discovered something remarkable about a type of star known as a Cepheid variable: the rate at which this type of star goes through a dim-bright-dim cycle is highly significant; it offers a way of finding out how far away the star is.

In the early 1920s, benefitting from access to the huge Hooker Telescope, Hubble found Cepheid variable stars located in nebulae. He paid close attention to the Andromeda nebula, and discovered that the Cepheid variables within the nebula are at tremendous distances from the earth, much farther than stars in our own Milky Way galaxy.

Hubble realized that the Andromeda nebula is actually a galaxy. Until then, most astronomers thought the Milky Way and the universe were the same thing. Hubble now knew that the universe was considerably bigger than the Milky Way, it contained other galaxies or 'island universes.'

Hubble found:

His best photographs of the outer parts of the Andromeda and Triangulum nebulae showed "dense swarms of actual stars."

Many of the stars were Cepheid variables.

The nebulae were located almost a million light-years † from Earth - four times farther away than anything observed before.

The Andromeda nebula's diameter exceeded 30,000 light-years††, making it bigger than the Milky Way.

The Andromeda galaxy emitted light of the order of a billion of our suns.

Three days after his thirty-fifth birthday, Hubble's discovery was announced - not in a scientific journal - but in The New York Times. His results had actually been circulating quietly among America's astronomers for some time: the official presentation came in a paper he submitted to be read at the January 1, 1925 meeting of the American Astronomical Society.

Hubble had changed our view of the universe forever. Our own vast galaxy, home to our sun and 100 billion other stars, is but one of billions of other galaxies.

In addition to this, Hubble gave us the system we use for classifying galaxies, shown below:

Red Shift is Directly Related to Distance

The eminent astronomer Vesto Slipher had also studied nebulae. In 1913, he had reported that light from nebulae was shifted to the red end of the spectrum.

He interpreted his discovery as a Doppler shift, one of the most familiar examples of which is the pitch of a police car's siren: if the car is racing towards you the pitch is raised; if it is racing away from you the pitch is lowered.

Light behaves in a similar way. Light emitted by an object racing away from Earth is shifted to the red end of the spectrum.

Slipher examined a number of nebulae - he did not know they were galaxies - and found light from a large majority of them showed a significant red shift, indicating they were moving away from Earth at prodigious speeds.

In 1929, Hubble took Slipher's red-shift data and combined it with red-shift observations he and his assistant Milton Humason had made. He plotted the red-shift data against galaxy distance data and found a remarkable correlation.

Hubble turned the relationship from his graph into an equation, now called Hubble's Law, which says:

where v is velocity, r is distance, and H is the Hubble Constant, which Hubble calculated to be 530 km s⁻¹ Mpc⁻¹. Today, with the benefit of much more sophisticated observational data and better distance calibrations, H is believed to be approximately 70 km s⁻¹ Mpc⁻¹.

The Expanding Universe

One interpretation of Hubble's Law is that we live in an expanding universe. Hubble did not believe there was enough hard evidence to support this interpretation of red-shifts.

In fact, although Hubble brought the scientific world's attention to Hubble's Law, the law was in fact discovered two years earlier by Georges Lemaître. Unfortunately for Lemaître, his work received little attention. Lemaître calculated H to be 625 km s⁻¹ Mpc⁻¹.

Not only did Lemaître discover 'Hubble's Law,' his interpretation of it is the one accepted by modern cosmologists. Lemaître used Albert Einstein's theory of general relativity to show that red-shifts would result naturally if the very fabric of space itself were expanding.

However, Hubble's point of view was perfectly logical. Although the existence of 'dark matter' in the universe often seems a modern concern, Hubble wrote that the red-shifts could only be justified as evidence for an expanding universe if the density of matter in the universe were much larger than had actually been observed. He said the density of matter needed to accept red-shifts as evidence of an expanding universe is:

Also, if Hubble, for the sake of argument, accepted that red-shifts were caused by an expanding universe, observational data led him to believe that the universe's rate of expansion was slowing.

The Expanding Universe - Very Tricky

As an illustration of just how tricky this field is, in 2011, Saul Perlmutter, Brian Schmidt and Adam Riess shared the Nobel Prize in Physics "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae."

However, in 2016, a joint report by physicists at the Niels Bohr Institute and University of Oxford said that an analysis of more data than used by the Nobel winners indicated that the evidence for an accelerating expansion fell short of that required for a discovery of fundamental significance.

No doubt an unchallenged picture of what our universe is doing and why it is doing it will emerge, but it might be some time yet.

Honors

Hubble received a large number of awards in his lifetime, including the Newcomb Cleveland Prize in 1924; the Bruce Medal in 1938; the Franklin Medal in 1939; and the Gold Medal of the Royal Astronomical Society in 1940. For his work in World War 2, when he was chief of ballistics and director of the supersonic wind tunnel laboratory at Aberdeen, Maryland, he was awarded the Legion of Merit in 1946.

Probably the greatest honor Hubble received, albeit posthumously, was the naming of the great space telescope for him. The Hubble Space Telescope has transformed cosmology, provided images of unmatched beauty, and yielded data that has driven both a better understanding of the universe and an ongoing realization that we do not know or understand everything yet.

Some Personal Details and the End

In February 1924, age 34, Hubble married Grace Burke Leib, a graduate of Stanford University. They had no children.

Hubble's main hobby was book collecting - particularly books relating to the history of science. He became a trustee of the Huntington Library in San Marino.

Curiously, for a man who achieved greatness, Hubble gained a reputation for eccentricities. As a young man, he left America as an all-American college graduate and returned from Oxford as a pipe-smoking English gentleman, complete with whimsical turns of phrase that even Bertie Wooster might have hesitated to use. Hubble also became prone to exaggerating some of the experiences of his earlier years, such as his sporting achievements.

Hubble's discovery of other galaxies made him famous. He featured on the front page of Time magazine in 1948, and he and Grace became close friends with the novelist Aldous Huxley and his wife Maria, and met many of Hollywood's stars.

In 1949, age 59, Hubble suffered a serious heart attack. He was nursed back to health by Grace, but had to reduce his working hours - no more long cold nights at the telescope were allowed.

Edwin Hubble died, age 63, of a stroke (cerebral thrombosis) on September 28, 1953 in San Marino, California. At his own request, his final resting place is not known and Grace destroyed his personal papers. When Grace died in 1980 she was buried in the same secret resting place.

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Further Reading
Edwin Hubble
The Realm of the Nebulae
Yale University Press, 1936

Edwin Hubble
The Observational Approach to Cosmology
Oxford Clarendon, 1937

W. S. Adams
Obituary: Dr. Edwin P. Hubble
The Observatory, Vol. 74, pp. 32-35, 1954

R. Berendzen and M. Hoskin
Hubble's Announcement of Cepheids in Spiral Nebulae
Astronomical Society of the Pacific Leaflets, Vol. 10, No. 504, pp. 425-440, 1967

Donald E. Osterbrock, Ronald S. Brashear, Joel A. Gwinn
Self-Made Cosmologist: The Education of Edwin Hubble
ASP Conference Series, Vol. 10, Evolution of the Universe of Galaxies; Proceedings of the Edwin Hubble Centennial Symposium, ed. by Richard G. Kron, pp. 1-18

Alexander S. Sharov, Igor D. Novikov
Edwin Hubble, The Discoverer of the Big Bang Universe
Cambridge University Press, 1993

William H. Cropper
Great Physicists: The Life and Times of Leading Physicists from Galileo to Hawking
Oxford University Press, 2004

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Lived 1889 - 1953. Edwin Hubble's work produced a dramatic change in people's beliefs about the universe, proving it is home to galaxies besides the Milky Way. Hubble showed we live in a universe of many galaxies separated by immense distances, each an isolated 'island universe.'

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http://galileoandeinstein.phys.virginia.edu/lectures/IslamicScience.htm
https://mathshistory.st-andrews.ac.uk/Biographies/Al-Tusi_Nasir/
https://mathworld.wolfram.com/TusiCouple.html

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http://galileoandeinstein.phys.virginia.edu/lectures/newton.html

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Michael Fowler, Physics Dept., U.Va.
Newton's Life

In 1642, the year Galileo died, Isaac Newton was born in Woolsthorpe, Lincolnshire, England on Christmas Day. His father had died three months earlier, and baby Isaac, very premature, was also not expected to survive. It was said he could be fitted into a quart pot. When Isaac was three, his mother married a wealthy elderly clergyman from the next village, and went to live there, leaving Isaac behind with his grandmother. The clergyman died, and Isaac's mother came back, after eight years, bringing with her three small children. Two years later, Newton went away to the Grammar School in Grantham, where he lodged with the local apothecary, and was fascinated by the chemicals. The plan was that at age seventeen he would come home and look after the farm. He turned out to be a total failure as a farmer.

His mother's brother, a clergyman who had been an undergraduate at Cambridge, persuaded his mother that it would be better for Isaac to go to university, so in 1661 he went up to Trinity College, Cambridge. Isaac paid his way through college for the first three years by waiting tables and cleaning rooms for the fellows (faculty) and the wealthier students. In 1664, he was elected a scholar, guaranteeing four years of financial support. Unfortunately, at that time the plague was spreading across Europe, and reached Cambridge in the summer of 1665. The university closed, and Newton returned home, where he spent two years concentrating on problems in mathematics and physics. He wrote later that during this time he first understood the theory of gravitation, which we shall discuss below, and the theory of optics (he was the first to realize that white light is made up of the colors of the rainbow), and much mathematics, both integral and differential calculus and infinite series. However, he was always reluctant to publish anything, at least until it appeared someone else might get credit for what he had found earlier.

On returning to Cambridge in 1667, he began to work on alchemy, but then in 1668 Nicolas Mercator published a book containing some methods for dealing with infinite series. Newton immediately wrote a treatise, De Analysi, expounding his own wider ranging results. His friend and mentor Isaac Barrow communicated these discoveries to a London mathematician, but only after some weeks would Newton allow his name to be given. This brought his work to the attention of the mathematics community for the first time. Shortly afterwards, Barrow resigned his Lucasian Professorship (which had been established only in 1663, with Barrow the first incumbent) at Cambridge so that Newton could have the Chair.

Newton's first major public scientific achievement was the invention, design and construction of a reflecting telescope. He ground the mirror, built the tube, and even made his own tools for the job. This was a real advance in telescope technology, and ensured his election to membership in the Royal Society. The mirror gave a sharper image than was possible with a large lens because a lens focusses different colors at slightly different distances, an effect called chromatic aberration. This problem is minimized nowadays by using compound lenses, two lenses of different kinds of glass stuck together, that err in opposite directions, and thus tend to cancel each other's shortcomings, but mirrors are still used in large telescopes.

Later in the 1670's, Newton became very interested in theology. He studied Hebrew scholarship and ancient and modern theologians at great length, and became convinced that Christianity had departed from the original teachings of Christ. He felt unable to accept the current beliefs of the Church of England, which was unfortunate because he was required as a Fellow of Trinity College to take holy orders. Happily, the Church of England was more flexible than Galileo had found the Catholic Church in these matters, and King Charles II issued a royal decree excusing Newton from the necessity of taking holy orders! Actually, to prevent this being a wide precedent, the decree specified that, in perpetuity, the Lucasian professor need not take holy orders. (The current Lucasian professor is Stephen Hawking.)

In 1684, three members of the Royal Society, Sir Christopher Wren, Robert Hooke and Edmond Halley, argued as to whether the elliptical orbits of the planets could result from a gravitational force towards the sun proportional to the inverse square of the distance. Halley writes:
Mr. Hook said he had had it, but that he would conceal it for some time so that others, triing and failing might know how to value it, when he should make it publick.
Halley went up to Cambridge, and put the problem to Newton, who said he had solved it four years earlier, but couldn't find the proof among his papers. Three months later, he sent an improved version of the proof to Halley, and devoted himself full time to developing these ideas, culminating in the publication of the Principia in 1686. This was the book that really did change man's view of the universe, as we shall shortly discuss, and its importance was fully appreciated very quickly. Newton became a public figure. He left Cambridge for London, where he was appointed Master of the Mint, a role he pursued energetically, as always, including prosecuting counterfeiters. He was knighted by Queen Anne. He argued with Hooke about who deserved credit for discovering the connection between elliptical orbits and the inverse square law until Hooke died in 1703, and he argued with a German mathematician and philosopher, Leibniz, about which of them invented calculus. Newton died in 1727, and was buried with much pomp and circumstance in Westminster Abbey, despite his well-known reservations about the Anglican faith.

An excellent, readable book is The Life of Isaac Newton, by Richard Westfall, Cambridge 1993, which I used in writing the above summary of Newton's life.

A fascinating collection of articles, profusely illustrated, on Newton's life, work and impact on the general culture is Let Newton Be!, edited by John Fauvel and others, Oxford 1988, which I also consulted.

Projectiles and Planets

Let us now turn to the central topic of the Principia, the universality of the gravitational force. The legend is that Newton saw an apple fall in his garden in Lincolnshire, thought of it in terms of an attractive gravitational force towards the earth, and realized the same force might extend as far as the moon. He was familiar with Galileo's work on projectiles, and suggested that the moon's motion in orbit could be understood as a natural extension of that theory. To see what is meant by this, consider a gun shooting a projectile horizontally from a very high mountain, and imagine using more and more powder in successive shots to drive the projectile faster and faster.

The parabolic paths would become flatter and flatter, and, if we imagine that the mountain is so high that air resistance can be ignored, and the gun is sufficiently powerful, eventually the point of landing is so far away that we must consider the curvature of the earth in finding where it lands.

In fact, the real situation is more dramatic: the earth's curvature may mean the projectile never lands at all. This was envisioned by Newton in the Principia. The following diagram is from his later popularization, A Treatise of the System of the World, written in the 1680's:

The mountaintop at V is supposed to be above the earth's atmosphere, and for a suitable initial speed, the projectile orbits the earth in a circular path. In fact, the earth's curvature is such that the surface falls away below a truly flat horizontal line by about five meters in 8,000 meters (five miles). Recall that five meters is just the vertical distance an initially horizontally moving projectile will fall in the first second of motion. But this implies that if the (horizontal) muzzle velocity were 8,000 meters per second, the downward fall of the cannonball would be just matched by the earth's surface falling away, and it would never hit the ground! This is just the motion, familiar to us now, of a satellite in a low orbit, which travels at about 8,000 meters (five miles) a second, or 18,000 miles per hour. (Actually, Newton drew this mountain impossibly high, no doubt for clarity of illustration. A satellite launched horizontally from the top would be far above the usual shuttle orbit, and go considerably more slowly than 18,000 miles per hour.)

For an animated version of Newton's cannon on a mountain, click here!

The Moon is Falling

Newton realized that the moon's circular path around the earth could be caused in this way by the same gravitational force that would hold such a cannonball in low orbit, in other words, the same force that causes bodies to fall.

To think about this idea, let us consider the moon's motion, beginning at some particular instant, as deviating downwards -- falling -- from some initial horizontal line, just as for the cannonball shot horizontally from a high mountain. The first obvious question is: does the moon fall five meters below the horizontal line, that is, towards the earth, in the first second? This was not difficult for Newton to check, because the path of the moon was precisely known by this time. The moon's orbit is approximately a circle of radius about 384,000 kilometers (240,000 miles), which it goes around in a month (to be precise, in 27.3 days), so the distance covered in one second is, conveniently, very close to one kilometer. It is then a matter of geometry to figure out how far the curved path falls below a "horizontal" line in one second of flight, and the answer turns out to be not five meters, but only a little over one millimeter! (Actually around 1.37 millimeters.)

It's completely impossible to draw a diagram showing how far it falls in one second, but the geometry is the same if we look how far it falls in one day, so here it is:

For one second, AB would be only one kilometer, so since AC is 384,000 km, the triangle ABC is really thin, but we can still use Pythagoras' theorem!

Thus the "natural acceleration" of the moon towards the earth, measured by how far it falls below straight line motion in one second, is less than that of an apple here on earth by the ratio of five meters to 1.37 millimeters, which works out to be about 3,600.

What can be the significance of this much smaller rate of fall? Newton's answer was that the natural acceleration of the moon was much smaller than that of the cannonball because they were both caused by a force: a gravitational attraction towards the earth, and that the gravitational force became weaker on going away from the earth.

In fact, the figures we have given about the moon's orbit enable us to compute how fast the gravitational attraction dies away with distance. The distance from the center of the earth to the earth's surface is about 6,350 kilometers (4,000 miles), so the moon is about 60 times further from the center of the earth than we and the cannonball are.

From our discussion of how fast the moon falls below a straight line in one second in its orbit, we found that the gravitational acceleration for the moon is down by a factor of 3,600 from the cannonball's (or the apple's).

Putting these two facts together, and noting that 3,600 = 60 x 60, led Newton to his famous inverse square law: the force of gravitational attraction between two bodies decreases with increasing distance between them as the inverse of the square of that distance, so if the distance is doubled, the force is down by a factor of four.

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Michael Fowler, Physics Dept., U.Va. In 1642, the year Galileo died, Isaac Newton was born in Woolsthorpe, Lincolnshire, England on Christmas Day. His father had died three months earlier, and baby Isaac, very premature, was also not expected to survive. It was said he could be fitted into a quart pot.

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네이버 블로그 | 교육부

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유용한 교육정보 ■ 뉴턴의 사과 ▲미국의 Babson College에 있는 뉴턴의 사과나무 후손(출처: 에듀넷) 자신의 의문을 해결하기 위한 노력 끝에 뉴턴은 사과가 아래로 떨어지게 만드는 어떤 힘이 있을 것이라 생각하였으며 , 이 힘이 바로 중력이라 하였습니다 . 즉 , 중력이 작용하기 때문에 사과가 아래로 떨어지는 것이고 , 이 중력은 우주에 있는 모든 물체 사이에 존재하는 힘이라고 생각하였습니다 .

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https://www.encyclopedia.com/people/science-and-technology/astronomy-biographies/ulugh-beg
https://mathshistory.st-andrews.ac.uk/Biographies/Ulugh_Beg/
https://www.turkestantravel.com/en/mirza-ulugbek/
https://uzbekistan.travel/en/o/mirzo-ulugbek/
https://mathshistory.st-andrews.ac.uk/Biographies/Ulugh_Beg/

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( b. Sulṭāniyya, Central Asia, 22 March 1394; d, near Samarkand, Central Asia [now Uzbek S.S.R.], 27 October 1449)

astronomy.

Ulugh Beg, which means "great prince," was a title that replaced his original name, Muhammad Taragay. He was raised at the court of his grandfather, Tamerlane, and from 1409 was the ruler of Maverannakhr, the chief city of which was Samarkand.

In contrast with his grandfather, Ulugh Beg was not interested in conquest but gained fame as a scientist. At Samarkand in 1420 he founded a madrasa, or institution of higher learning, in which astronomy was the most important subject. Ulugh Beg himself selected the scientists who taught there, first interviewing them to determine their qualifications. His madrasa differed from others of that time both in the content and in the level of the subjects taught there. Besides Ulugh Beg, the lecturers included Salāh al-Dīn Mūsā ibn Mahmūd (Qādī Zāda), and Ghiyāth al-Dīn Jamshīd al-Kāshī.

Four years after founding the madrasa, Ulugh Beg erected a three-story observatory. At the instigation of the jurists, however, the building was reduced to ruins by the beginning of the sixteenth century, and in time apparently disappeared. Its precise location remained unknown until 1908, when the archaeologist V. L. Vyatkin found its remains.

The main instrument of the observatory proved to be-not a quadrant, as Vyatkin thought-but a "Fakhrī sextant." A trench about two meters wide was dug in a hill, along the line of the meridian, and in it was placed a segment of the arc of the instrument. The part that is preserved, which was in the trench, consists of two parallel walls faced with marble, fifty-one centimeters apart.

The main use of the Fakhrī sextant was in determining the basic constants of astronomy: the inclination of the ecliptic to the equator, the point of the vernal equinox, the length of the tropical year, and other constants arising from observation of the sun. Thus it was built chiefly for solar observations in general and for observations of the moon and the planets in particular (an arc of 60° is sufficient). Other instruments used were an armillary sphere, a triquetrum, an astrolable, and a shāmila(an instrument serving as astrolabe and quadrant).

With the aid of the Fakhrī sextant one could determine at noon every day the meridional height of the sun, its distance from the zenith, and its declination; and from this information one could deduce the latitude and the inclination of the ecliptic, such that between the latitudeφ the distance from the zenith z, and the declinationδ there is the known relationship φ= z + δ. For example, lettingέ be the inclination of the ecliptic, the distance from the zenith at noon on the day of the summer solstice is z ₁=Φ-έ and on the day of the winter solstice z ₂=φ+έ,equations that lead toέ = x 1/2 ( z ₂ - z ₁). The value obtained by Ulugh Beg for the inclination of the ecliptic, ε = 23° 30' 17", differs by only 32" from the true value (for his time). According to him, the latitude of Samarkand was 39°37'33".

The radius of the Fakhrī sextant in Ulugh Beg's observatory was 40.04 meters, which made it the largest astronomical instrument in the world of that type. On the are of the sextant are divisions in which 70.2 centimeters corresponds to one degree; 11.7 millimeters (or, if rounded, 12 millimeters) represents one minute; 1 millimeter is five seconds: and 0.4 millimeter is two seconds. It has been experimentally established that with unrestricted time for observation and sufficient training of the observer, the value of the threshold of angular discrimination can be considered as two to five seconds. Thus the choice of the scale of the main instrument, and its smallest divisions, was made with consideration for the limits of angular discrimination.

An important result of the scientific work of Ulugh Beg and his school was the astronomical tables called the Zīj of Ulugh Beg or the Zīj-i Gurgāni (Guragon, the title of Genghis Khan 's son-in-law, was also used by Ulugh Beg). This work, originally written in the Tadzhilk language, consists of a theoretical section and the results of the observations made at the Samarkand observatory; the latter include actual tables of calendar calculations, of trigonometry, and of the planets, as well as a star catalog.

The basis of Ulugh Beg's trigonometric tables was the determination of sin 1° with great accuracy. One of the methods of solving this problem was Ulugh Beg's, and another was that of Al-;Kāshī. Both lead to the solution of the third-degree algebraic equation with the form.

where x = sin 1° . Solving this equation by an original method of subsequent approximations, one obtains

x = sin 1° = 0.017452406437283571.

In his trigonometric tables Ulugh Beg gives the values of sines and tangents for every minute to 45°, and for every five minutes from 45° to 90° the values of cotangents are given for every degree. Comparing the values of the sines of any angles-for example, 20°, 23° and 26°-with the corresponding true values, we obtain the following:

Also strikingly accurate is the study of the yearly movements of the five bright plants known in the time of Ulugh Beg, as is evident bleow:

According to Ulugh

Beg True Value

Saturn 12°13'39"

12°13'36" (d' Alembert)

Jupiter 30° 20' 34"

30°20'31" (d' Alembert)

Mars 191°17'15"

191°17'10" (Lalande)

Venus 224°17'32"

224°17'30" (Lalande)

Mercury 53°43'13"

53°43'3" (Lalande)

Thus the difference between Ulugh Beg's data and that of modern times relating to the first four planets falls within the limits of two to five seconds.

In the case of Mercury the difference is somewhat larger-ten seconds at most-because, of the planets mentioned, Mercury has the greatest orbital velocity. In addition, the eccentricity of its orbit is 0.206-that is, it is considerable in comparison with the eccentricity of the four other planets-while the greatest visible angular distance of Mercury from the sun's disk is only about 28°. These peculiarities of the planet make observation of it with the naked eye fairly difficult, and consequently have an adverse effect on the accuracy of the results of observation. The yearly precession was determined by Ulugh Beg to be 51.4", while the true value is 50.2.".

The situation is somewhat different with Ulugh Beg's values for the positions of the stars. After that of Hipparchus, the star catalog of Ulugh Beg was the second in seventeen centuries. It contains 1,018 stars, the positions of some of which were determined mainly from observations made at the Samarkand observatory, and others from observations made before the beginning of 1437 (A.H./841). The latter were taken from the star catalog of al-Sūfī, who apparently borrowed them from Ptolemy. Thus the star catalog of Ulugh Beg has great value, since it is basically original, but nevertheless was influenced by Ptolemy, at least in respect to its coordinates.

In 1941 an expedition under the leadership of T. N. Kari-Niazov discovered the tomb of Ulugh Beg in the mausoleum of Tamerlane in Samarkand. In contrast with the Islamic customs of burying the dead only in a shroud, Ulugh Beg lay fully clothed in a sarcophagus, in agreement with the prescription of the shariat; a man who died as a shakhid (martyr) had to be buried in his clothes. On the skeleton, traces of his violent death are clear: the third cervical vertebra was severed by a sharp instrument in such a way that the main portion of the body and an arc of that vertebra were cut off cleanly; the blow, struck from the left, also cut through the right corner of the lower jaw and its lower edge.

NOTES

1. Ulugh Beg, Zīj Guragoni, Biruni Institute of Oriental Studies, Uzbek S.S.R. Academy of Sciences, MS 2214, 1.11a.

3. Birjantsi, Sharh, Zīj Guragoni, Biruni Institute of Oriental Studieds, Uzbek S.S.R. Academy of Sciences, MS 704, 1. 49a.

4. J.B.J. Delambre, Historie de l' astronomie indenne orientale (Paris, 1787), 155.

5. Ulugh Beg., op. cit., II. 117b, 118a.

BIBLIOGRAPHY

See Abū Tahir Hoja, Samaria, from Tadzhik into Russian, V. L. Vyatkin, trans. (Samrkend, 1899): Z. Babur, Babur-name, M.A. Sale, trans. (Tashkent, 1948); V. V. Bartold, Istoria kulturnoy zhizni Turkestana ("History of the Cultural Life of Turkestan" Leningrad, 1927); F. Baily, "The Catalogues of Ptolomey, Ulug-Beigh, Tycho Brahe, Halley and Hevelius, Deduced From the Best Authorities, With Various Notes and Corrections," in Memoirs of the Royal Astronomical Society (London, 1843); G. Bigourdan, L'astronomie (Paris, 1925); F. Boquet, Histoire de l'astronomie (Paris, 1925); C. Brockelmann, Geschichte der arabischen Literature (Weimar, 1898); J. B. J. Delambre, Histoire de l'astronomie du moyen âge (Paris, 1819); I. Greave, Binae tabulae geographicae, una Nassir-Eddini Persae, altera Ulug-Beigi Tartari (London, 1652); and T. Hayde, Tabulae longitudinis et latitudinis stellarum fixarum ex obsevatione Ulug-beighi (Oxifor, 1665).

Also see T. N. Kari-Niazov, Observatoria Ulugbeka v svete novykh dannykh ("The Observatory of Ulugh Beg in the Light of New Information"; Tashkent, 1947); and Astronomicheskaya shkola Ulugbeke ("The Astronomical School of Ulugh Beg"; Moscow, 1950; 2nd ed., enl., Tashkent, 1967); P. S. Laplace, Précis de l'historie de l'astronomie (Paris, 1865); E. B. Knobel, Ulughbeg's Catalogue of Stars (Washington, D.C., 1917); Salih Zaki, Asar-i Bakiya (‐Eternal Monument" Constantinople, 1911); G. Sarton, Introduction to the History of Science, II (Baltimore, 1931); L. Sédillot, Prolégomènes des tables astronomiques d' Oloug-Beg (Paris, 1853); G. Sharpe, Tabulae longitudinis et latitudinis stellarum fixarum ex observatione Ulugbeighi (Oxford, 1767); V.P. Shcheglov, "K voprosu o geograficheskikh koordinatakh i azimute sekstanta observatorii Ulugbeka a g. Samarkande" ("Toward the Question of the Geographical Coordinates and the Azimuth of the Sextant at the Observatory of Ulugh Beg and of the City of Samarkand"), in Astronomicheskiy zhurnal, 30 , no. 2 (1953); H. Suter, Die mathematiker und Astronomender Araber und ihre Werke (Leipzig, 1900); and V. L. Vyatkin, "Ochet o raskopkakh observatorii Mirza Ulugbeka v 1908 i 1909 godkh" ("An Account of the Excavations of the Observatory of Mirz Ulugh Beg in 1908 and 1909"), in Izvestiya Russkago komiteta dlya izucheniya sredneī i vostochnoi azii, 2nd ser. (1912), no. 11.

T. N. Kari-Niazov

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( b. Sulṭāniyya, Central Asia, 22 March 1394; d, near Samarkand, Central Asia [now Uzbek S.S.R.], 27 October 1449) astronomy. Ulugh Beg, which means "great prince," was a title that replaced his original name, Muhammad Taragay. He was raised at the court of his grandfather, Tamerlane, and from 1409 was the ruler of Maverannakhr, the chief city of which was Samarkand.

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Mirzo Ulugbek was inspired by his passion for sciences and religious connections as he once said "the Muslim men and women must possess knowledge”
Timur, Ulugh Beg's grandfather, came from the Turkic Barlas tribe which was a Mongol tribe that was living in Transoxania, today essentially Uzbekistan. He united several Turko-Mongol tribes under his leadership and set out on a conquest, with his armies of mounted archers, of the area now occupied by Iran, Iraq, and eastern Turkey. He came from a background of strong army men and continued their path as well as pursued a career in the arts, poetry, sciences and maths.