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Nebulae in a bottle

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A little bit of art and crafting

Objects like galaxies and nebulae can be ideal subjects if you are thinking of mixing art with science. You can inspire your students by getting them to created amazing images of galaxies or the milky was very easily using watercolors. Here is an example tutorial:

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Watercolor Milky Way Sky Painting Demonstration

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Living in the Milky Way

What is a constellation?

History of the Universe

Coma cluster of galaxies

How light pollution affects the stars: magnitude readers

Model of a black hole

Black holes in my school

Galaxy classification and formation

Galaxy Zoo

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Aerospace Engineering

Throughout all modules, we’ve talked about many space missions. As you can imagine none of these missions would exist if not for the people who designed, tested and eventually built these mind-boggling, complicated, high-tech instruments and pieces of equipment.  Engineering is a key pillar in the business of studying the Universe. We could put them all under one name, say “Aerospace Engineers”, but like in astronomy there are many different categories and specializations. For example, some engineers focus on testing the aerodynamics of aircrafts while others focus on propulsion systems, or material strength and behavior. There are space system engineers, material engineers, ground segment support engineers and many others different careers in this field. Like scientists, engineers also specialize on different branches through their studies. Many different types of engineers could have the same basic degree and start focusing their studies on specific branches at a later stage. When looking at the official website of a mission, there is always a part that presents the team of the mission. Having a look at the people working on a mission and their background could be inspirational for students and could help them get some more ideas.  In the videos below, you can get some more information and inspiration to present career role models in your classroom.

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Studying the origin and evolution of our Universe is the field of expertise of cosmologists. Cosmology studies our Universe from the Big Bang to any the large scale property of our Universe. Multiple Universes, dark matter and energy, string theory are some of the concepts cosmologists study.

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What Is Cosmology and What Do Cosmologists Do? | Big History Project

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Intro to Aerospace Engineering | MITx on edX | Course About Video (Coming soon!)

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EU Space Awareness Career Interviews: Jorge Vago, Project Scientist // FULL 3 min version

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Interview for the EU Space Awareness Career Hub with Jorge Vago, Project Scientist. Link to the interview profile: http://www.space-awareness.org/en/careers/interview/dr-jorge-vago/

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Astronomy is a very general term to refer to scientists that study the Universe beyond our planet. We have already seen some branches like space weather and planetary science in previous modules. In fact, the objects found in the Universe, like those presented in this module are all so unique that astronomers specialize on specific objects. “Compact objects” for example is a branch of astronomy that studies object of dense matter like white dwarfs and neutron stars. “Stellar astronomy” focuses on the evolution of stars. Students could be blown away by even hearing such titles. What is important to understand though is that if they are interested in becoming astronomers, specialization comes later in their studies, and they don’t need to make up their minds while at school. Most astronomers start their studies with a physics or a mathematics degree.  In some cases, it could also be chemistry, biology or another degree. As they go through courses, they get an overview of all these amazing objects that are out there and can later decide what exactly it is they want to do.

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Inspiring a new generation of space explorers

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(Subt) Conferencia del Prof. Mark McCaughrean, Centro Europeo de Investigación y Tecnología Espacial

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LISA Pathfinder was launched in December 2015 and set out to detect gravitational waves. To be more exact, it will test the necessary highly demanding in accuracy technology required to measure gravitational waves. Gravitational waves come from places we can’t see with telescopes, like for example black holes. So being able to detect them will change radically the way we understand our Universe. For scientists, being able to detect gravitational waves, is like a person who until now could only see what is going on around him/her and suddenly starts to hear, too. Imagine the amazing new information he/she would receive!
https://youtu.be/qbqox08OC-A

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LISA Pathfinder - Window on the gravitational universe

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JWST is a NASA mission in collaboration with ESA and the Canadian space Agency. It is scheduled to launch in October 2018 and it will study the history of our Universe. It is the largest telescope ever constructed. In fact it is so big it will have to be launched in pieces and assembled in space!

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Webb Telescope Milestone: Completion of Telescope Element

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The Gaia mission, launched in December 2013, aims to produce a 3D map of the Milky Way helping scientists understand its composition formation and evolution. Gaia will make accurate measurements of the positions and motions of around 1% of the total population of stars in our Galaxy. To understand the accuracy with which Gaia is observing these stars, imagine that it can measure the width of a human hair at 2000 kilometres distance! Thus, Gaia is able to observe the positions of stars with a truly remarkable accuracy!

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Red giants and red supergiants

As we mentioned earlier, when stars burn hydrogen in their core, which is the better part of their lives, they are located in the main sequence of the H-R diagram. When hydrogen stock runs out, the star compresses its core in order to increase its temperature and continue producing energy by fusing helium into carbon. This compression is so abrupt that the outer layers of the star get detached, they start expanding and lose energy fast. This causes the star to get a lot bigger and red. This is the phase when a small star becomes a “Red Giant”. More massive stars, manage to get their core temperature high enough to fuse carbon and heavier elements all the way to iron. More massive stars become “Red supergiants” instead. Red giants can be 10 to 150 times bigger than the initial star. A star like our Sun, when it becomes a red giant will become about 2000 times brighter.

Red supergiants, that get to the point of fusing silicon to iron reach a core temperature of about 3 billion degrees. Their outer layers get so swollen, they can reach a diameter of a billion kilometres.

White dwarfs

Small mass stars (up to 8 solar masses) after going through the phase of red giants and their outer layers get blown away from the core of the star, what remains is basically their naked core. That naked core is what we call a “White Dwarf” which eventually cools down over billions of years and eventually becomes black. The core of the original star is now super dense (about a million  times the density of the sun), hot (about 100.000 degrees) pile of carbon ash roughly the size of the Earth, with incredible gravity. Imagine that a cough drop of white dwarf material equals the weight of a car on Earth! Normally, a white dwarf has such tremendous gravity, that it would collapse. However, this is not what happens thanks to quantum mechanics. Pauli’s exclusion principle and Heisenberg’s uncertainty principle keeps the mass from becoming any denser and thus the white dwarfs survives. Due to the quantum phenomena, the matter of white dwarfs is called “degenerate” which means it has some very peculiar properties. For example, the more massive the white dwarf, the smaller its size!

Planetary Nebulae

Depending on the mass of the star (as usual!) in some cases, when the outer shell of a star gets blown away, it will form something like a gaseous cloud around the white dwarf that remains. That is what we call a “Planetary Nebula”. Radiation emitted by the white dwarf will interact with the gases of the nebula causing it to emit light at different wavelengths.

What’s odd about nebulae is that, since they come from the outer shell of a star, one would expect them to be spherical. And yet they are not. They come in many different shapes.

Image Source (from left to right): NASA, NASA, Evangelos Souglakos

The reasons behind these shapes can be different, binary stars (two stars orbiting around each other) or planets orbiting the star could be a couple of these reasons. The gases of the nebulae vary; there is hydrogen but there can also be oxygen, sulfur and nitrogen. These gases emit in different colors of the spectrum. This is also why nebulae have such different colors. As nebulae came from the blowing away of the stars outer shell, they don’t remain still, they keep expanding. After a few thousands of years, they become very faint to observe. Their short life time is the reason why there are not so many of them on the sky. However, the size, color and shape of a nebula can tell us a lot about the life and death of the original star.

Neutron stars

When stars between 8 and 20 solar masses eventually stop producing energy through fusion, they don’t simply have their core exposed after their outer shell is detached. The phenomena taking place here are so extreme, they cause the star to collapse under its own gravity and explode. What remains is a core that has undergone so many extreme changes that is truly extraordinary. The gravity in the remains of the core of such stars is so huge that it overcomes electron degeneracy (which occurs in white dwarfs) and literally force electrons to smash into protons thus creating neutrons. Very few of them survive. So, what really remains, is a supermassive object made of neutrons with some protons, electrons and element left here and there. These objects also have a thin crust of heavier elements nuclei, like iron and electrons. Imagine something like a gigantic atomic nucleus. These are the “Neutron Stars”. Neutron stars are among the most bizarre objects of the Universe. They have a radius of about 20 km and the mass of an entire star. To understand how insanely massive these objects are, imagine that a cough drop of neutron star material would weigh as much as all humans on Earth combined.

Neutron stars (also called pulsars) also spin very rapidly (a few times per second) and they emit very accurate pulses.  The pulses they emit are so accurate and consistent that when first detected scientists believed it was not coming from a natural object but from extra-terrestrial life.

Think about introducing neutron stars to your students when you talk to them about atomic nuclei, the strong and weak interaction!

Black holes

For stars beyond 20 solar masses, the fate of a star is even more extreme. The gravity in such dying stars is so massive that nothing can stop it. After the star explodes it leaves behind what we call a“Black Hole”. A black hole, has such tremendous gravity that nothing can escape, it not even light. That’s why it’s black. In other words, the escape velocity* of a black hole is greater than the speed of light. Since not even light can escape a black hole, we can never really see it. The area around the black hole were the escape velocity is equal to the speed of light is called the “Event Horizon”. Nothing escapes once it passes that horizon. Black holes come in different sizes. The smaller can have as much as 3 solar masses. Unlike what some might thing they don’t suck all mass around it. Depending on the distance of an object from it, the object can actually orbit a black hole without being sucked in. However, if the object gets close enough, then it can indeed be pulled in by the black hole. It is believed that galactic centres are occupied by black holes and they could be playing a significant role in the evolution of galaxies.

*Escape velocity is the velocity an object needs in order to escape permanently the gravitational pull of another object. The escape velocity for an object in order to escape Earth’s gravity  for example is 11 km/sec.

As you may imagine, such staggering objects as black holes, also have very peculiar properties. For example, remember tides? In an earlier module we talked about how the Moon’s gravity affects the Earth and how tidal forces tend to stretch objects. Well, imagine what happens near an object with gravity so massive as a black hole’s! If an object like a tree was to fall in a black hole roots first, the gravity at the roots would be millions of times stronger than at the top of the tree, stretching it out to a thin line. And let’s not also forget about space-time! Gravity can affect space-time. The greater the gravity the slower time passes by. In fact, it slows down so much that at the event horizon it stops completely. So if we were standing near a black hole watching our tree pass the event horizon, time would freeze! We would watch the tree slowing down more and more taking infinite time to reach the horizon.

Image Source: NASA

Our students’ perception of gravity is usually limited up to the point of gravity holding planets together around their parent star. Black holes, like white dwarfs and neutron stars are excellent examples, to demonstrate to your students how powerful gravity can be in extreme situations.

Supernovae

When stars bigger than 8 solar masses come to a point when they can no longer produce energy through fusion the go out with a tremendous explosion and become either neutron stars or black holes. The explosions of these stars are called “Supernova”. In fact this is only one type of supernova. A white dwarf can also cause a supernova when it’s part of a binary system of stars. The white dwarf will take mass from its companion and when it has accumulated enough mass it will collapse under its own gravity causing a supernova. Supernovae release unforeseen amounts of energy in a very short amount of time, at speeds close to the speed of light. They enrich the interstellar medium with heavy elements. In fact, we wouldn’t be here if it wasn’t for supernovae. Perhaps you noticed earlier that even the largest of stars can fuse elements only reaching up to iron. Iron is the ultimate form of ash in the Universe. That’s because fusion beyond iron is not producing any energy, it requires more energy than it emits. Thus stars can’t fuse iron to produce energy. Particles beyond iron can only produce energy through fission. So if it wasn’t in the interest of stars to make all the other elements, how did they come to exist? The calcium in our bones? Gold? Platinum?

During supernovae, conditions are so extreme that fusion takes place even if it’s not in the benefit of the exploding star thus creating heavier elements. These heavier elements are also scattered through the interstellar medium during the blast of a supernova. Eventually, over long periods of time, gas and dust that make up new stars and their planets are enriched by these heavier elements that were created during supernovae explosions.  Bottom line? We are all made of stardust!

When introducing the periodic table, binding energy, fusion and fission in class, talking about supernovae and how these elements came to exist can be very inspiring for your students and give them an idea of how tightly our lives are bound to the Universe and the stars.

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What is Your Cosmic Connection to the Elements?

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In rare cases, the white dwarf itself can detonate in a massive explosion which astronomers call a Type Ia supernova. This occurs if a white dwarf is part of a binary star system, and matter accumulates slowly onto the white dwarf. If enough matter accumulates, then the white dwarf cannot support the added weight, and begins to collapse.

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Many observations indicate that some galaxies are close enough to interact through the gravitational force. Of course, it takes a tremendous amount of time to see any changes, so to us they seem as if they are standing still. Scientists have developed simulations to view such interactions in “fast forward”. Similar, simplified simulations are also created for educational purposes and can be a lot of fun for students. Here you can find two nice tools for your students and a quick activity that combines them:

You can use the “Observing with NASA” robotic telescope network to take an astronomical observation of different celestial objects. It can be used to take an observation of two interacting galaxies. Then use this “Galaxy Crash” simulation and try to tell the story of these galaxies. Based on the simulation students can understand how these two galaxies where before they started to interact, how much time has it been since they started interacting and what will happen to them in future. Here you can find the answer keys for playing with M51 and its companion and the antennae galaxy in a galaxy crash.

More about galaxies

Related theory on the classification of Galaxies

Galaxies

Types of Galaxies

Clusters of Galaxies

Discovery of Galaxies

Active Galactic Nuclei

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Our Universe Has Trillions of Galaxies, Hubble Study

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Galaxies are vast collections of stars that populate our universe. But how many galaxies are there? Counting them seems like an impossible task. Sheer numbers is one problem - once the count gets into the billions, it takes a while to do the addition. Another problem is the limitation of our instruments. To get the best view, a telescope needs to have a large aperture (the diameter of the main mirror or lens) and be located above the atmosphere to avoid distortion from Earth's air.

Perhaps the most resonant example of this fact is the Hubble eXtreme Deep Field (XDF), an image made by combining 10 years of photographs from the Hubble Space Telescope. The telescope watched a small patch of sky in repeat visits for a total of 50 days, according to NASA. If you held your thumb at arm's length to cover the moon, the XDF area would be about the size of the head of a pin. By collecting faint light over many hours of observation, the XDF revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the universe ever taken at that time. So if that single small spot contains thousands, imagine how many more galaxies could be found in other spots.

While estimates among different experts vary, an acceptable range is between 100 billion and 200 billion galaxies, said Mario Livio, an astrophysicist at the Space Telescope Science Institute in Baltimore, Maryland. The James Webb Space Telescope is expected to reveal even more information about early galaxies in the universe, according to The Astrophysical Journal.

According to Livio, the Hubble Space Telescope has been successful for galaxy counting and estimation. The telescope, launched in 1990, initially had a distortion on its main mirror that was corrected during a shuttle visit in 1993. Hubble also went underwent several upgrades and service visits until the final shuttle mission there in May 2009.

In 1995, astronomers pointed the telescope at what appeared to be an empty region of Ursa Major, and collected 10 days' worth of observations. The result was an estimated 3,000 faint galaxies in a single frame, going as dim as 30th magnitude, according to Weber State University. (For comparison, the North Star or Polaris is at about 2nd magnitude.) This image composite was called the Hubble Deep Field and was the farthest anyone had seen into the universe at the time.

As the Hubble telescope received upgrades to its instruments, astronomers repeated the experiment twice. In 2003 and 2004, scientists created the Hubble Ultra Deep Field, which in a million-second exposure revealed about 10,000 galaxies in a small spot in the constellation Fornax.

In 2012, again using upgraded instruments, scientists used the telescope to look at a portion of the Ultra Deep Field. Even in this narrower field of view, astronomers were able to detect about 5,500 galaxies. Researchers dubbed this the eXtreme Deep Field.

All in all, Hubble reveals an estimated 100 billion galaxies in the universe or so, but this number is likely to increase to about 200 billion as telescope technology in space improves, Livio told Space.com.

Counting stars

Whatever instrument is used, the method of estimating the number of galaxies is the same. You take the portion of sky imaged by the telescope (in this case, Hubble). Then - using the ratio of the sliver of sky to the entire universe - you can determine the number of galaxies in the universe.

"This is assuming that there is no large cosmic variance, that the universe is homogenous," Livio said. "We have good reasons to suspect that is the case. That is the cosmological principle."

The principle dates back to Albert Einstein's theory of general relativity. Einstein said that gravity is a distortion of space and time. With that understanding in hand, several scientists (including Einstein) tried to understand how gravity affected the entire universe.

"The simplest assumption to make is that if you viewed the contents of the universe with sufficiently poor vision, it would appear roughly the same everywhere and in every direction," NASA stated. "That is, the matter in the universe is homogeneous and isotropic when averaged over very large scales. This is called the cosmological principle."

One example of the cosmological principle at work is the cosmic microwave background (CMB), radiation that is a remnant of the early stages of the universe after the Big Bang. Using instruments such as NASA's Wilkinson Microwave Anisotropy Probe, astronomers have found the CMB is virtually identical wherever one looks.

Would the number of galaxies change?

Measurements of the universe's expansion - through watching galaxies race away from us - show that it is about 13.82 billion years old. As the universe gets older and bigger, however, galaxies will recede farther and farther from Earth. This will make them more difficult to see in telescopes.

The universe is expanding faster than the speed of light (which does not violate Einstein's speed limit because the expansion is of the universe itself, rather than of objects traveling through the universe). Also, the universe is accelerating in its expansion.

This is where the concept of the " observable universe" - the universe that we can see - comes into play. In 1 trillion to 2 trillion years, Livio said, this means that there will be galaxies that are beyond what we can see from Earth.

"We can only see light from galaxies whose light had enough time to reach us," Livio said. "It doesn't mean that that's all there is in the universe. Hence, the definition of the observable universe."

Galaxies also change over time. The Milky Way is on a collision course with the nearby Andromeda Galaxy, and both will merge in about 4 billion years. Later on, other galaxies in our Local Group - the galaxies closest to us - will eventually combine. Residents of that future galaxy would have a much darker universe to observe, Livio said.

"Civilizations started then, they would have no evidence that there was a universe with 100 billion galaxies," he said. "They would not see the expansion. They would probably not be able to tell there was a Big Bang."

What about other universes?

As the early universe inflated, there are some theories that say that different "pockets" broke away and formed different universes. These different places could be expanding at different rates, include other types of matter, and have different physical laws than our own universe.

Livio pointed out there could be galaxies in these other universes - if they exist - but we have no way right now of knowing for sure. So the number of galaxies could even be greater than 200 billion, when considering other universes.

In our own cosmos, Livio said, astronomers will be better able to refine the number with the launch of the James Webb Space Telescope (for which his institute will manage the mission operations and science). Hubble is able to peer back at galaxies that formed about 450 million years after the Big Bang. Using the James Webb telescope, astronomers anticipate they can look as far back as 200 million years after the Big Bang.

"The numbers are not going to change much," Livio added, pointing out the first galaxies probably formed not too long before that. "So a number like 200 billion [galaxies] is probably it for our observable universe."

Webb's contributions

While it is interesting to count the number of galaxies in our universe, astronomers are more interested in how galaxies reveal how the universe was formed. According to NASA, galaxies are a representation of how matter in the universe was organized - at least, on the large scale. (Scientists are also interested in particle types and quantum mechanics, on the small side of the spectrum.) Because Webb can look back to the early days of the universe, its information will help scientists better understand the structures of the galaxies around us today.

"By studying some of the earliest galaxies and comparing them to today's galaxies, we may be able to understand their growth and evolution. Webb will also allow scientists to gather data on the types of stars that existed in these very early galaxies," NASA said of Webb's mission.

"Follow-up observations using spectroscopy of hundreds or thousands of galaxies will help researchers understand how elements heavier than hydrogen were formed and built up as galaxy formation proceeded through the ages. These studies will also reveal details about merging galaxies and shed light on the process of galaxy formation itself."

According to NASA, here are some of the key questions Webb will answer about galaxies:

How are galaxies formed?

What gives them their shapes?

How are the chemical elements distributed through the galaxies?

How do the central black holes in galaxies influence their host galaxies?

What happens when small and large galaxies collide or join together?

Scientists are also interested in the role that dark matter plays in the assembly of galaxies. While some of the universe is visible in forms such as galaxies or stars, dark matter is what makes up most of the universe - about 80 percent of it. While dark matter is invisible in wavelengths of light or through emissions of energy, studies of galaxies dating back to the 1950s indicated there was far more mass present in them than what was visible with the naked eye.

"Computer models that scientists have made to understand galaxy formation indicate that galaxies are created when dark matter merges and clumps together," NASA said.

"It [dark matter] can be thought of as the scaffolding of the universe. The visible matter we see collects inside this scaffolding in the form of stars and galaxies. The way dark matter 'clumps' together is that small objects form first, and are drawn together to form larger ones."

Webb's powerful mirrors will allow scientists to look at galaxy formation - including the role of dark matter - up close. While this investigation doesn't directly answer how many galaxies there are in the universe, it does help scientists better understand the processes behind the galaxies we see, which in turn better informs models about galactic populations.

Additional resources

You can see thousands of galaxies, taken in one photograph, in this image taken by NASA's Hubble Space Telescope. To read more about the different types of galaxies, head to NASA's Hubblesite.

Bibliography

"Oases in the dark: galaxies as probes of the Cosmos". Astrophysics and Astronomy Commons (2007). http://sciencejedi.com/professional/talks/ynp_galaxies.pdf

"Galaxy number counts - V. Ultradeep counts: the Herschel and Hubble Deep Fields". Monthly Notices of the Royal Astronomical Society, Volume 323, Issue 4 (2001). https://academic.oup.com/mnras/article/323/4/795/1102609?login=true

"Finding High-redshift Galaxies with JWST". The Astrophysical Journal (2021). https://iopscience.iop.org/article/10.3847/1538-4357/ac2a2f/meta

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How many galaxies are there? Astronomers have an estimate, but accurately counting them depends on several factors.

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NASA.gov brings you the latest images, videos and news from America's space agency. Get the latest updates on NASA missions, watch NASA TV live, and learn about our quest to reveal the unknown and benefit all humankind.

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All-sky surveys from ESA's Planck space telescope

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The beginning of the universe, for beginners - Tom Whyntie

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How Do You Measure the Size of the Universe?

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Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

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Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

# data[].attributes.body
Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

# data[].attributes.body
Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

# data[].attributes.body
Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

# data[].attributes.body
Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

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Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

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Galaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years.

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The observable UniverseGalaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years. 

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The observable UniverseGalaxies are the neighbourhoods of stars. They are systems of hundreds of billions of stars but how many stars are there in the Universe? How can we count them? Can we see them all? Counting the stars is not an easy task for sure! First, we need to clarify that we can only speak about the stars that we can observe. This is why we often talk about the “Observable Universe”. That is the part of the Universe we can observe. Why can’t we see the entire Universe? Because light has a finite speed! A first estimation is that the observable Universe is as big as light could travel since the beginning of the Universe, which would be around 13.8 billion years ago. That means that the observable Universe could be around 13.8 billion years in radius. Well… not exactly. There are other factors to take into consideration, like the expansion of the Universe.  A photon that was born during the big bang and has travelled 13.8 billion years to reach us, by the time we detect it, it has travelled much further away from us than where it originally was, making the observable Universe much bigger than 13.8 billion light years. So how big is the observable Universe? Around 45.7 billion light years. 

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Gamma rays are produced at the core of the Sun due to nuclear fission processes. However the high densities in the Sun’s inner part (remember the photons’ random walk?) and the constant interactions of the produced photons with the plasma in the Sun, make these photons lose a big part of their energy, so from gamma ray photons they become photons of lower energy radiation. However, some gamma rays are emitted from the Sun because of solar flares. The solar corona is also responsible for the emission of ultraviolet radiation and X-rays. However, these make up only a small fraction of the total energy and radiation emitted. Ultraviolet radiation (in the form of UV-A, B, and C radiation) is mostly absorbed at higher altitudes. Extreme ultraviolet and soft X-ray radiation is also mostly absorbed by the atmosphere at high altitudes (around 96 km). Although soft X-ray radiation is absorbed by the atmosphere, it can be quite dangerous to living organisms. Such electromagnetic radiation with short wavelengths, can indeed be harmful to people as they can interact with molecules on our skin and give us sunburns or effect our DNA. Visible, infrared light and radiation of lower frequencies ( longer wavelengths) on the other hand, do not harm humans. Instead, this radiation reaches the Earth’s surface, keeping it warm and habitable. Here is a graph about the amount of energy emitted from the Sun at different wavelengths:

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The Sun emits electromagnetic radiation of many different frequencies. Some types of radiation (those with high frequency) can be harmful to humans and we need to be protected from them as they can interact with our skin giving us sunburns or effect our DNA causing more serious problems. Luckily for us a total amount of this kind of radiation that reaches the Earth’s surface is relatively small. The greatest amount of electromagnetic radiation coming from the Sun is for radiation between 100 and 1000nm, so between near ultraviolet to far infrared. Its pick is around the wavelengths of visible light. It is no coincidence that human eyes have evolved to detect the electromagnetic radiation that is emitted the most from the Sun!

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The Sun’s electromagnetic radiation

The Sun emits energy that is crucial for life on Earth. The amount of energy received on Earth affects our climate and all subsystems of our planet. Let’s see a little bit about solar radiation itself.

To many people the term ‘electromagnetic radiation’ is identified with some kind of dangerous radiation that is harmful to living organisms. However, this is not exactly the case. Electromagnetic radiation is in fact light. Depending on the wavelength (or frequency) of the radiation, we have different bands - from gamma rays to visual light and radio waves. Visible light is the only type of electromagnetic radiation that is visible to humans. Some animals and insects have the ability to see colors beyond the visual spectrum. Before talking about solar radiation let’s see a few things about electromagnetic radiation in general, to clarify some misconceptions.

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The colour of the Sun

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Think about the color of the sun. You thought "yellow" right? Well the physics of light is playing a little trick on you. It all depends on where you are. Read more: http://www.techinsider.io/ FACEBOOK: https://www.facebook.com/techinsider TWITTER: https://twitter.com/businessinsider INSTAGRAM: https://www.instagram.com/businessinsider/ TUMBLR: http://businessinsider.tumblr.com/

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Schiaparelli would perform a test landing on Mars and it was supposed to analyse the local environment (studying among others wind, humidity, pressure and temperature) for a few days. Unfortunately, on October 19, Schiaparelli, crashed on Mars as it deployed its parachute too early and fired its thrusters for an insufficient amount of time. You can see here its descent sequence.

The 2016 Trace Gas Orbiter’s (TGO) mission is to gain a better understanding of methane and other atmospheric gases that are present in small concentrations (less than 1% of the atmosphere) but nevertheless could be evidence for possible biological or geological activity. The instruments onboard the Trace Gas Orbiter will be deployed to detect a wide range of atmospheric trace gases (such as methane, water vapor, nitrogen oxides, acetylene), with an improved accuracy of three orders of magnitude compared to previous measurements.

Source: http://exploration.esa.int/mars/46475-trace-gas-orbiter/

The Exomars rover will be launched on 2020. The primary objective is to land the rover at a site with high potential for finding well-preserved organic material, particularly from the very early history of the planet. The rover will establish the physical and chemical properties of Martian samples, mainly from the subsurface. Underground samples are more likely to include biomarkers, since the tenuous Martian atmosphere offers little protection from radiation and photochemistry at the surface.
The ExoMars Trace Gas Orbiter, part of the 2016 ExoMars mission, will support communications.

Mars activity book

Mars for educators

Return to Mars activities

Role model - Meet Jorge Vago, the 2020 Exomars mission Project Scientist

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Establishing if life ever existed on Mars is one of the outstanding scientific questions of our time. As ESA mentions “To address this important goal, the European Space Agency (ESA) has established the ExoMars programme to investigate the Martian environment and to demonstrate new technologies paving the way for a future Mars sample return mission in the 2020's.

Two missions are foreseen within the ExoMars programme: one consisting of the Trace Gas Orbiter plus an Entry, Descent and landing demonstrator Module (EDM), known as Schiaparelli, launched on 14 March 2016, and the other, featuring a rover, with a launch date of 2020. Both missions will be carried out in cooperation with Roscosmos.”

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Saturn activities from NASA: NASA has a number of activities designed around Saturn. You can explore some of them here.

Explore Saturn and Titan at School with ESA: ESA offers a cartoon-style teaching aid with fact sheets for teachers to use in the classroom as well as a series of videos that can be used in class.

Cassini-Huygens paper model

SpaceScoop article “Countdown to Cassini’s grand finale”

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Cassini-Huygens is a joint NASA/ESA/ASI mission. NASA's Cassini spacecraft continues to orbit Saturn, making an extensive survey of the ringed planet and its moons. The ESA Huygens probe is the first to land on a world in the outer Solar System - on the surface of Titan, Saturn’s largest moon. Data from Cassini and Huygens may offer clues about how life began on Earth.
The Cassini-Huygens spacecraft was launched on October 15, 1997 and entered the Saturnian system on July 1, 2004. On 25 December 2004, towards the end of the third orbit around Saturn, the Cassini orbiter jettisoned the Huygens probe for its 20-day journey to Titan during which its instruments provided valuable information and pictures of Titan’s atmosphere.

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ESA Euronews: Saturn probe could tell us more about life on Earth

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Juno and mythology: You may want to link the Juno mission and the myth behind Juno the ancient roman goddess. Juno’s Greek equivalent is Hera and in Etruscan mythology is Uni. Talk to your students about how different ancient myths still inspire people to this day.

Juno and arts/crafts: The images received from Juno are absolutely stunning (check NASA’s website photo gallery). You can use these images as art inspiration for your students or work with your students to recreated some of them, exploring the colors and the shapes. Additionally, you may want to use the Spacecraft paper model to have some fun with your students while exploring the spacecraft’s instruments and structure.

Juno and science: NASA has designed a many activities for students around the Juno mission. You may want to have a look at the "Explore Jupiter's Family Secrets" guide for students between 8 and 13. For older students, you can explore the Juno's "SpaceMath"resources.

Participate in the mission with JunoCam: NASA invites amateur astronomers to send their pictures and help scientists decided what images to take during the spacecraft’s flybys using the JunoCam.

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The Juno Spacecraft got its name after the Roman goddess Juno, Jupiter’s wife. Jupiter would hide himself under a veil of clouds to hide from his wife but Juno was able to see through the clouds and find out his indiscretions. Like the goddess, Juno the spacecraft aims to peer thought Jupiter’s swirling cloud tops and discover what lies underneath.

Juno set out to understand the origin and evolution of Jupiter. It was launched on August 5, 2011 and it successfully entered the orbit of Jupiter on July 4, 2016. For the first time, we will be able to peer below the dense cover of clouds to answer questions about the gas giant and the origins of our solar system.

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Jupiter: Into the Unknown (NASA Juno Mission Trailer)

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So now that we have thought a little about the ‘why’, let’s think a little bit about the ‘what’.  It certainly makes sense to give some basic information about the planets and all other objects that comprise our Solar System. There are fun ways to do that like a card game or a ‘guess who’ game.

When talking about the basics of the Solar System, many teachers choose to focus on the scale. Giving your students a proper understanding of the scales of our Solar System and ensuring that the models presented to them are correct is an important point. To this end when creating such models, here is an idea on how to do it using the correct scales.

As it is too difficult to have the Sun and all the planets in the correct dimensions, perhaps you could consider building two separate models. One showing the Sun with respect to the planets (Image 1), and one that introduces the planets alone (Image 2).

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So now that we have thought a little about the ‘why’, let’s think a little bit about the ‘what’.  It certainly makes sense to give some basic information about the planets and all other objects that comprise our Solar System. There are fun ways to do that like a card game or a ‘guess who’ game.

When talking about the basics of the Solar System, many teachers choose to focus on the scale. Giving your students a proper understanding of the scales of our Solar System and ensuring that the models presented to them are correct is an important point. To this end when creating such models, here is an idea on how to do it using the correct scales.

As it is too difficult to have the Sun and all the planets in the correct dimensions, perhaps you could consider building two separate models. One showing the Sun with respect to the planets (Image 1), and one that introduces the planets alone (Image 2).

Image 1, Via: Wikimedia commons

https://commons.wikimedia.org/wiki/File:Planets_and_sun_size_comparison.jpg

Image 2, Via: Wikimedia commons

https://commons.wikimedia.org/wiki/File:Size_planets_comparison.jpg

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The Solar System is made up of the Sun and all of the smaller objects that move around it. Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.

Beyond Mars is the asteroid belt - a region populated by millions of rocky objects. These are left-overs from the formation of the planets, 4.5 billion years ago.

On the far side of the asteroid belt are the four gas giants - Jupiter, Saturn, Uranus and Neptune. These planets are much bigger than Earth, but very lightweight for their size. They are mostly made of hydrogen and helium.

Until recently, the furthest known planet was an icy world called Pluto. However, Pluto is dwarfed by Earth's Moon and many astronomers think it is too small to be called a true planet.

An object named Eris, which is at least as big as Pluto, was discovered very far from the Sun in 2005. More than 1,000 icy worlds such as Eris have been discovered beyond Pluto in recent years. These are called Kuiper Belt Objects. In 2006, the International Astronomical Union decided that Pluto and Eris must be classed as "dwarf planets".

Even further out are the comets of the Oort Cloud. These are so far away that they are invisible in even the largest telescopes. Every so often one of these comets is disturbed and heads towards the Sun. It then becomes visible in the night sky.

Last modified 07 August 2014

Related articles

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The Solar System is made up of the Sun and all of the smaller objects that move around it. Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.

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One of the problems teachers almost always face is that they don’t have enough time to work on the Solar System with their students or that it is very little (if at all) discussed in the curriculum of their countries. So are there any opportunities to bypass this problem?

Aside from having dedicated classes with your students about the Solar System, you can also use fun facts like those we mentioned above, ad hoc in your class, as inspiration or food for thought and discussion. Talking about the Solar System does not necessarily need to happen all at once; you can keep feeding your students with information through different classes. This approach can help you not only spice up your everyday teaching, it can also facilitate you in helping your students understand that all science disciplines are connected and to their total, they are used to describe the same thing, our world!

Finally have a look at some activities for your students:

Know your planets

"Our Solar System, journey to other celestial objects"

NASA's eye application

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"The only mystery of the Universe, is that there is a mystery of the Universe" Fernando Pessoa.

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Brief description: Use Space Scoop astronomy news stories for children as the basis for a creative writing and drawing activity.

Keywords: Space Scoop, storytelling, drawing, literacy, art, creative, journalism

Time: 2-3 hours

Level: Primary school

Age: 8+

Materials needed: Multiple copies of several Space Scoop releases (available at www.eu-unawe.org/kids), crayons, a pen and paper (or a computer)

Learning objectives: Getting familiar with astronomy and science journalism and improving creative thinking, literacy and teamwork skills.

Background information: While professional astronomers strive to further our understanding of the Universe, science communicators are doing an equally important job: sharing this new knowledge with the public. Astronomy communication is especially important for children, where the aim of highlighting exciting new discoveries is to inspire them to develop an interest in science and technology.
Full description of activity:
EU Universe Awareness (EU-UNAWE) has created an astronomy news service for young children, called Space Scoop (www.eu-unawe.org/kids). The idea behind Space Scoop is to change how astronomy and space sciences are often presented to young children as historical subjects. By sharing exciting new astronomical discoveries with them, we aim to inspire them to develop an interest in science and technology.

In addition to being a fantastic resource to introduce young children to the world of science, Space Scoop can also be used as reference material by teachers for developing lessons in creative writing and drawing.

Step 1: Print out lots of different Space Scoop releases. Divide the children into groups in different parts of the classroom and distribute the articles so that the children only see the Space Scoop that they are working on.

Step 2: Tell the children to imagine that they are in a spaceship (they can be human or alien) and that they can see the astronomical object(s) or event mentioned in the Space Scoop release.

Step 3: Ask them to write a description of the object(s) or event in the form of an eyewitness account. Emphasise the need to use lots of adjectives.

Alternative: Ask the children to re-tell the Space Scoop in the form of a poem.

Step 4: Tell the children to swap their stories with someone from a different group. Then ask them to draw a picture of the astronomical object or event described by their classmate. The drawing must be based solely on the eyewitness account and not on the original Space Scoop.

Step 5: Ask the children to pair up with the person that they swapped their story with. Are the drawings similar to what the storytellers had imagined the objects or event would look like when writing their eyewitness accounts (or if they are similar to the picture used in the Space Scoop)? If they are different, ask them to try to figure out why. Could the storyteller have included more description to help the reader? Or is this astronomical object or event so strange and bizarre that there are many possible ideas for what it may look like, all of which are equally right? Do professional astronomers even know how it reallylooks?
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Brief description: Use Space Scoop astronomy news stories for children as the basis for a creative writing and drawing activity. Keywords: Space Scoop, storytelling, drawing, literacy, art, creative, journalism Time: 2-3 hours Level: Primary school Age: 8+ Materials needed: Multiple copies of several Space Scoop releases (available at www.eu-unawe.org/kids), crayons, a pen and paper (or a computer) Learning objectives: Getting familiar with astronomy and science journalism and improving creative thinking, literacy and teamwork skills.

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Remind anyone of a favorite arcade game? The new moon passes over the sun in this Feb. 21 image taken by NASA's Solar Dynamics Observatory. The partial eclipse was visible only from space.

The next partial solar eclipse Earthlings will be able to see will occur May 20, with views visible from Asia, the Pacific and western North America.

Credit: NASA/SDO

On Sunday (May 20), a solar eclipse will blot out the sun for viewers across much of Asia, the Pacific and western North America. These days, eclipses aren't a big mystery - they occur when the moon passes between Earth and the sun. But throughout history, the sun's significance, along with its mysteriousness, have yielded an array of solar myths.

From the fearsome figures that try to devour the sun to nine lost suns of the Chinese sky, here are the stories that have sought to explain our nearest star.

How Hou Yi shot the sun

In ancient Chinese mythology, the sky had not one, but 10 suns. Every day, the solar goddess Shiho would pick up one of these suns (also her sons) and wheel him across the sky in her chariot. In the meantime, the other nine would play among the leaves of the mythical Fusang tree, believed to be more than 10,000 feet tall. [ Gallery of Sun Gods and Goddesses]

This system worked well until the day that the suns grew bored of their responsibility. They decided to run across the sky all at once, planning to generate enough light and heat so that they could all take a few days off. Instead, this solar scamper dried up rivers, scorched the Earth and led to widespread drought.

Taking pity on suffering mortals, the sun god Dijun called in the expert archer Hou Yi. With 10 magic arrows, the story goes that Hou Yi was to discipline the irresponsible suns. The archer stalked and killed nine suns and would have snuffed out the last as well if a young boy hadn't stolen his final arrow, saving Earth from perpetual darkness.

Ancient Chinese myth also holds that solar eclipses were caused by a demon or dragon devouring the sun, leading to a tradition in which people would play drums or bang pots to scare the sun-eater away. In actuality, Chinese astronomers seemed to understand eclipses as natural phenomena dating back at least as far as 720 B.C., with older observations scratched into bones dating back perhaps 3,000 years.

Chased by wolves

In ancient Norse legend, the sun goddess Sol travels through the sky chased by the wolf Sköll, who intends to devour her. (Sköll's brother Hati does the same to the moon at night.) Eclipses were said to be a sign that Sköll was dangerously close to catching Sol.

In fact, the Norse believed that one day, the sun would finally be devoured. Mythology foretold a huge battle called Ragnarök, in which major gods would die and the Earth would be engulfed in a massive flood. This apocalypse would wipe the Earth, clean to be repopulated by a pair of human survivors. [ Top 10 Ways to Destroy Earth]

Sailing the sun boat

One of the most important deities in the Egyptian pantheon was Ra, the falcon-headed sun god. Legend had it that every day Ra captained a boat crewed by gods across the sky. (This boat was called Mandjet, or the "Boat of Millions of Years" - an underestimate, given that our star is actually about 4.5 billion years old.)

At night, Ra returned to the east via the underworld, bringing light to the dead. It was a treacherous journey: Apep, an evil serpent god, attempted to stop Ra by devouring him. Solar eclipses were thought to be days when Apep got the upper hand, though Ra always managed to escape.

Jealous star

According to a Cherokee legend, the sun long ago grew jealous of her brother the moon because the people of Earth always looked at her with twisted-up faces and squinted eyes, while they smiled at his gentle light. The sun's daughter lived in the middle of sky, so every day, the sun stopped to visit her. Angry at humans for their ugly expressions, the sun began using these opportunities to send down so much heat that people began to die of fever.

The humans turned to the Little Men, who in Cherokee legend were friendly, magical spirits who dwelt in the forests. The Little Men said that the sun must die, so they turned one man into a rattlesnake and another into a fearsome antlered serpent called the Uktena.

The rattlesnake arrived at the sun's daughter's house to wait for her arrival. But while he was waiting, the sun's daughter opened her door. The rattlesnake accidentally bit her, killing her. When the sun came to see her daughter, she discovered her dead and began to weep, flooding the Earth with her tears.

Desperate to please the sun and stop the weeping, the people of Earth made an attempt to rescue the dead daughter from the land of ghosts, but failed. When they returned, the sun began to weep even harder. To distract her, the people began to dance and play music until she finally became happy again.

Slowing down the sun

The Maori people of New Zealand tell a tale about a long-ago time when the days were shorter than they are now. The hero Maui often heard his brothers lamenting the lack of light during the day. He decided to solve the problem by taming the sun. Although his brothers were skeptical, they and their tribe helped Maui weave a net out of flax.

Maui and his brothers then set out to the east to find the sun's resting place. They covered the entry to the sun's cave with nets and smeared themselves with clay to protect against the sun's heat. When the sun emerged, it fought and struggled in the nets, but the brothers held firm. Maui began to beat the sun - some stories say he had an ax, others a club made of the jawbone of an ancestor - until the star was so weakened that it could no longer race across the sky. According to the legend, that is why the sun travels so slowly in the sky today.

You can follow LiveScience senior writer Stephanie Pappas on Twitter . Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on .

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On Sunday (May 20), a solar eclipse will blot out the sun for viewers across much of Asia, the Pacific and western North America. These days, eclipses aren't a big mystery - they occur when the moon passes between Earth and the sun.

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There are some common misconceptions that we often find among students (and in some cases adults as well). Let’s see the most common ones:

1. The Sun is a unique object in the Universe.

Our Sun may be unique in the sense that it is the star that supports life on Earth, but other than that, it is anything but unique. Our Sun is a star. A medium-sized star to be exact. There are stars that are 10 times smaller and stars that are 50 times bigger. It is just like the stars we see on the night sky. The only reason we see it so big and during the day is because it is very close to our Earth compared to all other stars. To get an idea how close, our Sun is about 150 million kilometers away from Earth, while the next nearest star (Proxima Centauri) is 4.24 light years (or 9,460,730,472,580 km!) away. To put it in perspective, light from the surface of the Sun reaches Earth in 8.3 minutes, while from the surface of Proxima Centauri to Earth in needs 4.24 years.

2. The Sun is about the size of the Moon. This is why we have total eclipses.

The Sun has 1.4 million km diameter, while the Moon is a little less than 3 500 km across. The reason why we have eclipses is their relative position to Earth. To help your students understand that, ask a student to stand still and another to move away far enough so that the first student can cover the second with his/her thumb. Is the second student really the size of a thumb?

3. The Sun is a ‘quite’ ball of fire.

As we have seen in the information presented above, the Sun is not ‘quite’. It is not like a switched-on lightbulb that simply emits light. There are numerous events and phenomena going on constantly. Solar activity follows an 11-year solar activity during which the Suns activity differs.

Activities for students:

Tracking Sunspot using real data

Solar Rotation

Calculation of the Sun's effective temperature

Safe Sun Viewer

Make your own Sunflower

Observing the sun for yourself

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Fun Fact: When looking at an eclipse, one can tell if the Sun is going through an active or quite period by looking at the solar corona. The material there and the streams they follow can ‘show’ us what the Sun’s magnetic field looks like during that period. When the Sun is in a low activity period, we can "see" indirectly the lines of its magnetic field (Image A). When the Sun is in a high activity period, there are many sunspots and flares, which involve very intense magnetic fields. Thus, the lines of the magnetic field are not so clear (Image B).

Image A: Solar eclipse 2008 (low Solar activity)

Image credit: Fred Espenak

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Every approximately 11 years, the Sun’s poles flip. North becomes South and vice-versa. The Sun behaves more or less the same regardless which pole is North and which South. During this 11 year-cycle solar activity varies. As we go towards the peak of a solar cycle, the Sun is much more active, meaning that there are a lot more sunspots (appearing mostly around the equator) many more flares, Coronal Mass Ejections and other related features.

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The sun and its atmosphere consist of several zones or layers.

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Nikos Nerantzis and Eleftheria Baka implemented this course with 11 students from the second and third class for the Public Special Junior High School of Thessaloniki. These students have different special educational needs and/or disabilities. Teachers are expected to handle a diverse class and keep the balance while keeping the students interested and engaged.

Let’s have a look at what they did.

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Public Special Junior High School of Thessaloniki

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Nikos Nerantzis and Eleftheria Baka share with us their experience from implementing the Solar System didactic course with students of the Public Special Junior High School of Thessaloniki.

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Solar System didactic course for primary education.

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Aside from its own story, the Moon can tell us a lot about the history and formation of our Solar system and our own planet. This is why there are scientists who focus their research entirely on the Moon. “Selenology” or “Lunar Science” is a branch of science that focuses on studying the origin, the nature and the physical features of our Moon. Among others, Selenology includes Selenography which includes the mapping and studying of the Moon’s surface features.  Geologists can obtain an abundance of information about the Moon’s composition, studying rocks brought to Earth by lunar missions and thus understand much about the Moon’s history.

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"Conditions on the Sun and in the solar wind, magnetosphere, ionosphere and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health."

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Although the Sun is a star like billions of others. It has one property that makes it very unique. Its proximity to Earth. We in fact live within its extended atmosphere. Thus, our Sun can be studied in much greater detail than any other star. Heliophysics is a branch of astrophysics dedicated to the study of the Sun, its nature and impact in space.

You can find out more about heliophysics here.

One of the most important phenomena that take place on the Sun is the gases streams that the Sun ejects which can pass past the Earth at incredible speed (about 500km/sec). We refer to these streams as solar wind. Solar wind can have an effect on the Earth’s magnetic field. It can affect or damage satellites, threaten the life of astronauts and cause problems to power stations and power lines on Earth.  Space weather studies how solar wind and the phenomena that take place on the Sun affect the Earth and other planets. As technology progresses, space weather starts to play an increasingly important role. Scientists study in great detail phenomena that are related to space weather like CMEs, solar flares and sunspots in order to understand them and protect human infrastructures.  Here is a video on space weather.

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Luna programme and future lunar missions

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Luna programme and future lunar missions

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NASA wasn’t the only one aiming at the Moon. Luna was a robotic spacecraft programme designed by the Soviet Union which launched 15 successful missions (orbiters or landers) between 1959 and 1976. Three of these missions (Luna 16, 20 and 24) managed to collect 300 grams of lunar soil from three different sites and bring it back to Earth.

Since then, missions have been limited to lower orbit missions (less than 500km from the Surface of the Earth).  However, lunar missions did not come to an end in the 1970’s. The Moon is once again among the destinations of future missions. Have a look at the video below to learn more:

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solar and heliospheric observatory (spacecraft)

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NASA | Highlights from SOHO's 20 Years in Space

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Dr. Joe Gurman of NASA's Goddard Space Flight Center provides commentary on selected shots from SOHO's 20 years in space. After 20 years in space, ESA and NASA's Solar and Heliospheric Observatory, or SOHO, is still going strong.

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solar and heliospheric observatory (spacecraft)

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SOHO Mission: Discovery of more than 3000 Comets!

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Since the launch of the SOHO Mission nearly 20 years ago, NASA and the European Space Agency's Solar and Heliospheric Observatory has spotted 3000 comets. The mission's The Large Angle and Spectrometric Coronagraph (LASCO) instrument blocks out the bright solar disk, making it easier to see the corona of plasma and dust around the Sun, normally only visible during solar eclipses.

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Happy Birthday SOHO!
We are celebrating 25 years since the launch of SOHO...

Two and a half decades of scientific discovery is a major milestone for any space mission. But when the spacecraft at the heart of the celebration was only designed to last for two years,..

JHelioviewer is new visualization software that enables everybody, anywhere to explore the Sun...

read the story "

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Solar and Heliospheric Observatory Homepage

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Happy Birthday SOHO! We are celebrating 25 years since the launch of SOHO... Two and a half decades of scientific discovery is a major milestone for any space mission. But when the spacecraft at the heart of the celebration was only designed to last for two years,..

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NASA | Highlights from SOHO's 20 Years in Space

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I work near Imperia (Italy).
I am a foreign languages teacher with a specialisation in special needs education so I teach every subjects to students with special needs at the Secondary School.
I grew with the idea that I was not gifted for Science, but observing my Science colleagues I find their lessons very interesting and motivating for students and now I believe that Science is fascinating and can be for everyone.
I love travelling around the world physically and virtually and reading makes me travel with my mind  :)

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https://youtu.be/4gjnn9kSwDk

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Intuitive drawing (or painting) and personal geography are two widely known art techniques through which the artists try to develop their imagination and reflect on themselves or different situations. These are fun activities you could also do with young students. The Moon is an excellent starting point for both.

If you have young students, you can stir up their imagination by giving them a picture of the full Moon and ask them to draw anything that the areas of the Moon reminds them of. This is a little intuitive drawing activity, similar to the game we often do with cloud shapes when trying to imagine what they could depict.
Students can also engage in a little personal geography activity. Ask your students to create their own map of the Moon, by naming the Maria, highlands and craters using names of their choosing. The names the students could think of using could be the names of their family members, their favorite heroes, their favorite football team, words that remind them of happy memories, they can be anything the students come up with!