https://padlet.com/vfoushee0001/pq75jcm01xzfwex5 A timeline depicting the discoveries of astronomers in relation to the model of the solar system en-us 2022-01-26 22:47:13 UTC 2025-11-07 17:09:11 UTC hello@padlet.com https://padlet.net/icons/png/1f30c.png ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014675909 (384-322 B.C.)
Geocentric
The Earth is at the center of the universe and all celestial objects revolve around it in perfect circles.
It didn't explain why planets changed brightness and retrograde motion.
Source]]> 2022-01-26 23:01:35 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014675909 ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014679765 (100 AD-170 AD)
Geocentric
Ptolemy proposed a solution to Aristotle's model, arguing that the planets moved in two sets of circles known as a deferent and an epicycle while sharing the belief that the Earth was at the center of the geocentric model with his predecessor.
Ptolemy's model had many moving parts with some appearing coincidental, such as why Mercury and Venus stay by the sun, with all planets themselves treated independently and hard to figure out the order of as a result. In all, the geocentric solar system proposed didn't make sense as a physical explanation.
Source]]> 2022-01-26 23:06:16 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014679765 ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014683535 (1473-1543)
Heliocentric
The model made by Copernicus positioned the Sun motionless at the center of the Universe, with Earth and other planets orbiting it in circles at uniform speeds, although modified in areas by the inclusion of epicycles.
While he correctly placed the Sun at the center, Copernicus believed the Sun to not only be the middle of the solar system but the universe as a whole. His model also neglected the reality of elliptical orbits, supplementing them with various epicycles in his system, a problem similar to that of Ptolemy.
Source]]> 2022-01-26 23:11:01 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014683535 ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014685950 (1571-1630)
Heliocentric
Similar to Copernicus, Kepler's model was heliocentric with every planet orbiting the Sun, although, unlike his predecessor, Kepler believed that the planets formed elliptical paths rather than circular ones.
Kepler held a strong belief in the existence of only six planets, claiming it to be due to there being only five Platonic shapes with each needing to fit between the orbit of two planets. However, his theory on said front was later proven false.
Source]]> 2022-01-26 23:14:16 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014685950 ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014689911 (1564-1642)
Heliocentric
With the construction of his own telescope in 1609, Galilei improved it significantly and discovered the four biggest moons on Jupiter, forming concrete proof that not everything in the sky orbited the Earth. This revelation, among others, helped prove that the Sun was at the center of the Solar System instead of the Earth, supporting the Heliocentric model.
While Galilei's model shares numerous similarities with that of present-day's belief of the solar system, Galilei, due to not discovering Neptune, neglected to include the planet in his theory.
Source]]> 2022-01-26 23:19:20 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014689911 ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014853002 (Circa 595~610 AD)
Queen Seondeok was very interested in astronomy. Under her reign, Cheomseongdae, possibly the oldest astronomical observatory in the world was established. It was used to predict the weather by following the pattern of the stars. Built in Gyeongju, South Korea, it remains not only the oldest surviving astronomical observatory in Asia, but possibly the world.
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Source 3]]> 2022-01-27 01:50:52 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014853002 ccasey0006 https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014894316 (Around 16th century-present day)
Heliocentric
Following the heliocentric model, the modern-day belief of the solar system includes the Earth and planets revolving around the sun, instead of vice versa. Although a mathematical model of the system was only presented by the sixteenth century by Copernicus before being supported by Kepler and Galilei, it continues to persist to this day.]]> 2022-01-27 02:24:05 UTC https://padlet.com/vfoushee0001/pq75jcm01xzfwex5/wish/2014894316