Great job to team 99075A, inVEXtus, for winning the excellence award at the Martinsburg Qualifier! I’m really proud of all their hard work! This qualifies them for the state competition and a national invitational if we choose to attend. As the coach, I could not be more pleased. This is why we advocate for unconventional education, the students have learned so much, not just in stem but also durable skills, without even recognizing it. For reference of who’s who, from left to right is Dolly Bharti:mentor, Vijay Bharti:coach, Jihan Park: team member, and Maria Tsetylin: team member
Sorry for blur in the photo, the camera is slightly obstructed.
We are almost done with the planets, I hope your trip through the Solar System has been fun 😀
The next planet that comes after Jupiter and before Neptune is Uranus. It has a day of 17 hours and a year equal to 84 years on Earth. Just like Jupiter and Saturn are similar, Uranus and Neptune are very similar. Uranus was the first planet to be discovered in the sky, noticed by Herschel. It is visible in the night sky, if you have very good vision and a very dark sky, but more likely than not you will need a decent telescope to see it. Uranus probably has a small rock core, a large mantle made of water and ammonia which can get very hot.
The Catch with the Core
Notice how I say probably when discussing the core. I may have not brought this up before but we do not even know with certainty what Earth’s core is made of. We have made deductions of its composition of iron and nickel because of data like the magnetic field behavior here on Earth. We cannot access the core to know what it has. Thus, knowing for Uranus is even more difficult since we can not observe nearly as much of this data, like seismic wave behavior. The conclusion that it has a small rock core comes from the fact that since it is so massive, the pressure at the core must form some solid rocky core.
Back to the Facts
There is also methane in the mantle, which can reach very hot temperatures. At these high temperatures, the methane can break down and reform into complex hydrocarbons. This can form diamonds naturally there! The atmosphere also contains a lot of methane. Methane absorbs a lot of red light so that is why Uranus is blue. The clouds on this planet are made of ammonia, hydrogen and hydrogen sulfide. It is also sideways, so it orbits from south to north. This happened likely due to something massive impacting Uranus and turning it sideways, such that the poles are now side to side. It has only been visited by the Voyager 2 spacecraft. Just like Saturn, Uranus has rings, they are just must less pronounced. Finally, Uranus has over 2 dozen moons.
Here are some facts on the Voyager 2 spacecraft that I retrieved from NASA. It is the only spacecraft to have observed Uranus and has taken some stunning pictures.
Moons of Uranus
Uranus has 27 Moons, all named after characters written about by Shakespeare. The largest moon, Titania, was discovered by William Herschel, along with the second largest, Oberon. Another individual, William Lassell, discovered Ariel and Umbriel. There are many other moons orbiting this planet, like Puck, Miranda, and Portia. The moon Miranda has all sorts of crazy features like giant valleys.
Here is a picture of the moon Miranda. There are many well defined craters, valleys, and other varying land features.
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
Here is the end of our trip through the Solar System, we have reached the final planet, Neptune. If you are wondering, Pluto is not considered a planet because it has not cleared all the space debris in its orbit. It is considered a dwarf planet(this is debated often so it may change).
A day on Neptune is about 16 hours, and one year is 165 Earth years.
Neptune is likely similar to Uranus, and it is much larger, 17 times Earth’s mass whereas Uranus is 14.5 times. It is also azure blue, where Uranus is teal green. Neptune also has a lot of methane, but its almost equal to Uranus so the color difference is odd. In the post on Uranus, I explained that it is blue because methane absorbs red light, and only reflects the blue light, so we see it as blue. Since Neptune has nearly equal amounts of methane, it is odd that there is a significant color difference. This is likely caused by other components in the atmosphere, though it could be a variety of different factors.
This first image shows a comparison of Uranus and Neptune, with Neptune on the left. The color difference is very obvious but not well explained.Here is a nice info graphic from NASA outlining the Hubble Telescope, which has recently stopped operating and is to be replaced with the James Webb Telescope
Neptune has a very active atmosphere, where the winds can reach 2000 km/hr. A storm was seen on the planet by Voyager 2 in 1989 and is known as the Great Dark Spot. However, it dissipated by 1994 when it was observed by Hubble Telescope, and a new one appeared in 2016. So this spot appears to come and go, and it is not known why as far as I understand. Even though Saturn is the planet known for its rings, it is not the only planet to have them. Neptune does also, it has 3 main rings, 2 of which are thin and one is broad It has over a dozen moon. The largest of Triton, 2700 km wide and orbits in retrograde motion.
Here is a photo of Neptune’s largest moon, Triton
Atmosphere: The Great Dark Spot
Neptune has a similar atmosphere to Uranus, it is 80% Hydrogen gas, 19% Helium gas, and a little less than 1% Methane. The 1% of Methane accounts for the planet’s blue-green color. This planet has the strongest winds in the whole Solar System. The most unique thing about the planet is the Great Dark Spot, a storm the size of Earth. This was first observed by Voyager 2 spacecraft in 1989, but was determined to have disappeared in 1994 by the Hubble Telescope. The storm has recently reappeared, however, so it is understood to be much like Jupiter’s Great Red Spot except smaller and having a short life span. It also is relatively clear of clouds in the interior.
The dark spot in the middle of the planet is the Great Dark Spot. Because it is such a violent storm, it has immense pressure and caused disturbance among the gases, causing the dark color.
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
Saturn is quite an exciting planet to look at because of the prominent rings around it. Saturn is the 6th planet from the Sun, orbiting between Jupiter and Uranus. A day on Saturn is 10 hours and 42 minutes, while a year is 29 Earth years. Saturn is of similar volume to Jupiter but has significantly less mass. The basic facts about Saturn are very much like Jupiter, it is most hydrogen gas. Since it is so gaseous, Saturn is actually less dense than water! If you are looking in the night sky, it is the last planet you can see with just your eyes(granted, because of light pollution, we generally cannot see it).
Titan is the second largest moon in the Solar System and has a very thick nitrogen based atmosphere, it is also -180 Celsius there. The spacecraft Huygens landed on Titan to learn more about it. Titan has hydrocarbon dunes, which is cool because hydrocarbons are organic compounds. Cryo-volcanoes on Titan spew cold water instead of lava, so it may have liquid water under the surface. There were quite a few flat lakes of liquid methane which can cause streams that look like long valleys when observed. The second major moon, Enceladus, is about 500 km across, which has many cracks and cryo-volcanoes. The third major moon, Iapetus, is shaped like a walnut. Finally, Hyperion, the fourth major moon, looks like a huge Styrofoam which many holes.
These are the moons of Saturn. Titan is the largest of them and Mimas accounts for the resonance seen in the Cassini Division.
Rings of Saturn
The rings of Jupiter are believed to have been formed by one of Saturn’s moons that broke apart. Since the rings are ice, this moon must have been icy. The rings are 10 meters thick and each is given a letter based on order of discovery, with A being the first discovered and the farthest from the planet(since it was the farthest it would be seen first). The A ring is outside the B ring which is the widest and in that is C ring At first the A and B were thought to be connected but Giovanni Cassini discovered they aren’t, the gap between the two is known as the Cassini division. It is 5000 km across. But this gap it also has objects that orbit due to and in the exact same motion as one of its moons, Mimas. This is called resonance and it essentially means that every time Mimas completes an orbit around Saturn, these objects compete a proportional amount of orbits. This is generally two orbits per orbit of Mimas, so it is known as a 2:1 resonance orbit. There also exists and F ring, outside the A ring is very thin, made so by two moons, Pandora and Prometheus. There are internal rings beyond C which are D and E. F, or the outermost, was last discovered because of how thin it is, so do not get confused. See the picture below because it shows the positions of each ring.
The order of the rings, with D being closest to the planet itself.
The Atmosphere of Saturn
The atmosphere of Saturn is 96% Hydrogen, 3% Helium, and has a small amount of other gases like methane and sulfur. This sulfur makes clouds have a yellow tint. One special thing observed on Saturn is a hexagonal storm at the North Pole. It operates much like the Jet Stream on Earth but is much stronger. It also looks very cool!
The dark gray hexagon on the top is the storm on Saturn.
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
The next planet after Mars is Jupiter, but the distance between Mars and Jupiter is 3.68 AU(1 AU is the distance between the Earth and the Sun!). This is because there is an expansive Asteroid Belt that separates them. Jupiter is the first of the gas giants, and it is giant, in fact, around 1,300 Earth sized objects would occupy the volume of Jupiter. Compared to the Sun, however, it is extremely tiny. A day on Jupiter is only 10 hours, because the huge mass causes it to spin very quickly. This is the shortest day in the entire Solar System. The length of day can be predicted quite well based on the mass of the planet. Notice how Jupiter has a day much less than Earth because it is 300 times more massive than Earth, while Mercury has a day much longer than Earth because it is so tiny in comparison. A year on Jupiter takes 10 years on Earth. A cool fact about Jupiter is that it is very bright, you are very likely to be able to see it in the night sky if you go out(remember that planets do not twinkle, that is how you can identify them). Jupiter has dark stripes and bright stripes that are visible very clearly. The dark stripes are belts and the bright ones are zones. They oppositely orbit. The zones are made of ammonium gas. The belts form from the sinking of the belts. Turbulence between these zones and belts can cause storms. The great red spot is a huge storm that has speeds of 500 km/hr. The redness is formed by cyanide reflecting the red light. The size is shrinking. Jupiter has a very thick atmosphere of several hundred kilometers. Below the gassy atmosphere is liquid metallic hydrogen and the atmosphere is made of hydrogen, helium and ammonium. It is possible that Jupiter doesn’t have a core, and that the whole thing is just the gas and liquid that we have discussed. It is also possible that several large proto-planets formed Jupiter, which means it has a core. This could make sense because of the strong magnetic field exhibited by Jupiter, but then again it is not certain. It is most likely for the “core” to just be molten metal(such as metallic hydrogen). Jupiter emits more heat than it absorbs. This powers the atmosphere of Jupiter to have belts and zones. In 1994 Shoemaker Levy 9, a comet, impacted Jupiter many times, scarred the planets for months. This was the first time we could actually observe collision of objects in our Solar System. A cool belief about Jupiter is that because it is so massive(300 times the mass of the Earth but only 1/1000th that of the Sun) it can actually have an effect on the orbit of asteroids and comets, and actually pull them towards itself. This could mean Jupiter protects our planet from extraterrestrial debris. Finally, there are 67 confirmed moons around Jupiter, but 4 major ones to discuss, Ganymede, Callisto, Io, and Europa.
A depiction of the Belts and Zones that are visible on Jupiter. Image from Tarbuck and Lutgens Earth Science
Moons of Jupiter
Jupiter has 4 major moons, Ganymede, Callisto, Europa, and Io. These were discovered and observed by Galileo, so they are called the Galilean Moons. The largest is Ganymede which is over 5000 km wide! It has an ice crust and is differentiated, which means that the heavy elements like Iron are at the core and the lighter compounds, like silicates, form the mantle and crust(ice is another major compound that has the lighter behavior). Ganymede has oceans of water underneath its surface.
Callisto is the second largest of 4800 km. The surface is ice rich and is very cratered. It orbits furthest out from Jupiter, which means that it could be pulled out of Jupiter’s orbit. Jupiter is so massive, however, that this has not happened.
Io is a little bigger than Earth’s moon, and is orbiting the Jupiter every 12 hours. It is yellow and has over 400 active volcanoes. This material is rich in sulfur, causing the yellowness that is seen. This sulfur is actually pulled out of the atmosphere by other neighboring moons, which forms a radiation belt around Jupiter.
The smallest Galilean moon is Europa, and it is very reflective. This showed the surface was very flat, implying something resurfaced the moon, but it doesn’t have any craters. It also has large and long streaks, implicitly formed by upwelling of material form the interior of water. The amount of water in Europa may be more than all the water in the oceans of the Earth. Thus, it is possible that Europa may have enough to have life.
As a final fact about the moons, both Ganymede and Io are magnetically connected with Jupiter, they transfer charged particles to the moon and effectively cause aurora much like how the solar wind causes Earth’s aurora .
The 4 Galilean Moons
The Atmosphere of Jupiter
Since Jupiter is a gas giant, you can consider most of it to be its atmosphere. The atmosphere is mainly hydrogen and helium gas. Notice that this is the same as the Sun. Jupiter has similar properties to the Sun, the only problem is that in order for a planet like Jupiter to become a star, it must be at least 1/12th the mass of the Sun. Jupiter is only 1/1000th this mass.
Anyhow, 90% of the atmosphere is Hydrogen and 10%is Helium. That is approximate though, as a very little bit of the atmosphere is methane and ammonium and other gases. Zones and belts are formed in the atmosphere and circulate in counterclockwise direction because of differences in pressure. The zones are higher in the atmosphere and belts are lower.
As a final point, the Great Red Spot is a giant storm formed by very high pressures in the region. It functions just like a hurricane, just on a much larger scale. In fact, the Great Red Spot is more than double the size of Earth and has wind speeds of 270 miles per hour!
A picture of the Great Red spot. It circles like a hurricane around a point
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
Mars is the 4th planet in increasing distance from the Sun, and is the last of the terrestrial, or rocky, planets. One day on Mars is equal to one day and 37 minutes Earth time. It takes 687 days to orbit around the Sun. It is half the size of Earth, and has a thin atmosphere which causes large temperature fluctuations. Mars is red because of rust, or Iron Oxide. Mars rock is basaltic rock, which is quite mafic (rich in iron). Thus, basaltic rock, which is usually gray/black, easily becomes red colored because the iron in the rock forms rust with the oxygen in the atmosphere. However, oxygen is less than 0.5% of the atmosphere of Mars, with 95% being Carbon Dioxide. Thus, it is theorized that Mars had much more Oxygen in its atmosphere in the past. This atmosphere could have been lost due to Mars not having a magnetosphere of its own. For reference, a magnetosphere is a magnetic field around a planet formed by the metals within the planet’s core. This magnetic field protects against things like the solar wind, which eliminate an atmosphere. Finally, Mars has two moons, Phobos and Deimos. These are very tiny moons. Phobos rotates faster than Mars and is expected to collide with Mars in a few million years.
Surface of Mars
Mars has a rocky surface like Earth, and also has mountains, craters, and volcanoes. An interesting feature is that their is a significant elevation difference between the Northern and Southern Hemisphere. The Northern Hemisphere is much lower than the Southern, though it is much younger(formed by volcanic activity). The Tharsis bulge is the a large bulge of volcanoes on Mars, home to the largest volcano Olympus Mons. Valles Marineris is a large crack on mars 200 km wide and 4000 kilometers long. Mars has barchan dunes, which are sand dunes that make a crescent shape because wind blows in one direction, and even dust devils which are like small tornadoes of dust. Like Earth, Mars has a rocky surface, with the Northern Hemisphere
This is a picture of barchan dunes on Mars. The curvature is caused by wind pushing the center of the dunes inward.
This is a picture of a dust devil on Mars
The Atmosphere of Mars
Mars has a thin atmosphere, it is 0.6% of Earth’s atmosphere. This atmosphere is composed 95% of Carbon Dioxide, with the vast remainder being Nitrogen Gas. Other gases that compose the atmosphere include Argon, Oxygen, Carbon Monoxide, Water, and Nitrogen Oxide. Winds are common from this atmosphere and can cause things like the dust devils discussed above. Infrequently, these dust devils can form on a global scale. Finally, because of the thin atmosphere and the large distance to the Sun, Mars stays relatively cold. Even though the atmosphere is mostly carbon dioxide, which we know is a major greenhouse gas, this is by percent, not by quantity. Since the atmosphere itself is so little, the amount of carbon dioxide is small itself.
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
One post is not enough for Earth, after all, there are many subjects that attempt to describe it. However, I will do a brief overview of our planet in a similar fashion to that of the previous planets. Earth is 93 million miles away from the Sun(this is 1 AU), has a rotational period of 24 hours(one day), and a revolution period of 365.25 days(1 year) around the Sun. What makes our planet unique is that all the prerequisites are met that allow for life, such as having water and having organic compounds. We all know the Earth is round(with the exception of some) but it is not a sphere. When you think of round you probably think of a sphere and assume that the Earth is one, after all, it looks like one in every picture we have of it from space. However, it is called an oblate spheroid, which means two things. Oblate means stretched out, and this applies to Earth in that it is stretched at the Equator such that the poles are flattened. Spheroid means it is like a sphere, but is not exactly one, for Earth this is because rather than being smooth and round, it is quite bumpy. Once thought about, this is to be expected, because the Earth has been impacted by all sorts of extraterrestrial debris. Earth is oblate because of its rotation. Simply put, this rotation requires the particles to be at a larger distance at the Equator to stay in orbit. I have explained this in much detail in the next section. Finally, The Earth rotates about its axle tilted 24.5 degrees from the vertical. This is likely because of something impacting Earth. This something has been hypothesized to be a Mars sized object that hit Earth 4 million years ago and is also responsible for forming the Moon(this is the giant impact hypothesis).
The tilt of Earth
Why Is the Earth not a Sphere?
Unless you are interested in the physics of this question, I would recommend to skip this section, it is long. However, it can help you understand why the Earth bulges at the Equator if you do not want to just take this as fact.
This high speed rotation creates a centripetal force, which is proportional to the square of the angular velocity and the radius(distance from center). Without this force, the Earth would be a sphere, so let us take that as a starting point. Now the sphere starts spinning, and at a uniform angular velocity(it rotates at the same speed). The particles in the atmosphere at the north pole are really close to the axis of rotation(the line through the middle of the Earth that the planet rotates around) while the particles at the Equator are far away from this axis. This means two things for the particles at the Equator, and vice versa for the Poles; gravity is weaker on these particles and the rotate farther away from the axis(gravitational force is from the center of the earth and decreases as distance increases from the center). One thing is constant, however, these particles rotate at the same angular velocity whether at the poles or at the Equator.
We know that at the Equator, gravity is less. In order for these air particles to stay in orbit of Earth(and not get released), the centripetal force must be higher to account for this lessened gravity. Since angular velocity is constant, the only thing that can do this is an increase in radius. This means that at the Equator, the particles must be farther away from Earth in order for this centripetal force to be larger(this may sound counter intuitive but remember the centripetal force is directly proportional to radius). This is why there is a slight bulge at the Equator, making it oblate.
Surface of Earth
We all know of the surface of Earth as we live on it, so I will just give some of the important facts to know. I will make a full series on the Earth where you can read more about this. Since Earth is a terrestrial planet, it has a rocky surface, which is called the crust. This is broken into plates known as the tectonic plates. 71 percent of this crust is covered by the oceans, which is 360 million square kilometers. The surface on land is a granitic rock called granodiorite, which is similar to granite but has more quartz and feldspar. Meanwhile, ocean crust is basaltic, which is rock formed from lava.
Earth’s Atmosphere
I have already made a post on Earth’s atmosphere, so to learn about it, click this link! Once I have an Earth Science blog going, I will go in more detail on the atmosphere there also.
For Educators
Teaching about the Earth is no simple task, and probably should be done over many months. There is a lot to teach, so be creative! You have to teach about things like the orbit of the planet, the rock composition, and the atmosphere. The best way to do this is using hands-on activities, for example, bring in a bunch of different rocks and help students figure out how to identify them. Then relate these rocks to the crust and have students go outside and search for rocks and explore the dirt to see what composes it!
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
Venus is the second of the four terrestrial planets with regard to distance from the sun. This distance is about 67 million miles, so about 70 percent of Earth’s(which is 93 million miles). The mass of Venus is 4.9*10^24 kilograms. An interesting thing about Venus’s orbit is that it is retrograde in comparison to Earth’s. This simply means that Venus rotates in the opposite direction that Earth does(rotation is the spin of the planet, revolution is the orbit around the Sun). Somethings can appear to move in retrograde across the sky, such as other planets like Jupiter, because of the way our orbits work. When the Earth starts passing Jupiter, for example, it looks like the planet is going backwards in the sky(West to East), even though both Earth and Jupiter orbit the Sun in the same direction. This is called apparent retrograde motion and is caused simply by Earth passing Jupiter, and once it passes, Jupiter appears to move forward again. Anyhow, Venus is believed to have a molten core, not solid, because of the small mass of the planet. It likely does not exert enough pressure to be totally solid, just like Mercury. What makes Venus special is just how hot it gets. Venus has the thickest atmosphere out of all the planets, and it is mostly carbon dioxide. You likely already know that carbon dioxide traps heat; it is a greenhouse gas. In small quantities on Earth, we see temperatures rise. However it makes up less than one percent of the atmosphere. In Venus, 97 percent of the atmosphere is nothing but this gas! Thus, even though Mercury is closer to the Sun, Venus is the hottest planet, and it has a relatively stable temperature. This can go up to 880 degrees Fahrenheit!
Surface of Venus
Venus has a rocky surface like Earth, and also has mountains, craters, and volcanoes. It also has very long lava channels, the longest is called Baltis Vallis and is 6800 kilometers long. Volcanoes on Venus are generally shield volcanoes, which are very wide volcanoes but are short. The largest volcano is Maat Mons. The most notable fact about Venus’s Surface is that although it has craters, these are sparse and overall the surface is very smooth. These large, and smooth, regions are called basaltic plains, because the smooth rock is basalt. This type of rock is formed by the slow cooling of lava. Remember how volcanoes are very abundant, so every time a volcano erupts massive amounts of lava flows out of these shield volcanoes. This lava spreads over the surface of the planet and very slowly cools(the surface can reach 880 Fahreinheit so this “cooling”, which is solidification of the lava. takes an extremely long time). Since it cools so slowly, it becomes very smooth and thus forms these smooth plains, rather than being rugged and bumpy. Over time, you may expect this surface to get rugged with craters from asteroids, but it is not so. This is best explained by the lava cooling being very recent(past couple million years), so not much has been able to impact it, along with this new surface covering up all the old craters.
This is a picture of Maat Mons, the largest volcano on Venus
The Very Thick Atmosphere Of Venus
Venus has a very thick atmosphere, with the pressure from the atmosphere being 90 times that of Earth’s! That would be the pressure 900 meters deep underwater(this could crush many things). The atmosphere is mainly(96%) carbon dioxide, or CO₂, gas, which allows for it to trap heat in very well. This massive amount of this gas accounts for why Venus is so hot. The rest of the atmosphere is mainly nitrogen gas(3%). In the remaining 1%, a unique occurrence of sulfuric acid occurs. Since Venus is so hot, the sulfuric acid is evaporated and forms clouds. Specifically, this happens because of the interaction of SO₂ and H₂O(sulfur dioxide and water), which forms this acid. Acid rain on Earth happens the same way, but since this acid is not common at all(the acid rain on Earth is because of pollutants), we do not see clouds of it happen. On Venus, the sulfuric acid is more common so it is able to vaporize and form clouds.
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
Mercury orbits at 38 thousand kilometers from the Sun and weighs 3.285 × 10^23 kg, which is about a tenth of the weight of Earth. It orbits the sun once every 88 days(We orbit the Sun once every 365 days, which constitutes a year). Mercury has the most elliptical orbit out of all the planets. Planets do not orbit the Sun in a circle, but rather as an ellipse(an oval) which is explained by Kepler’s Laws. The year to day ratio of mercury is 2/1. This means that one day on Mercury is 2 years on Mercury! That sounds awfully confusing but to understand, the year to day ratio of Earth is 1/365. This means each year, 365 days occur. A day of a planet is how long it takes for the planet to turn one full rotation(360 degree). A year of a planet is how long it takes for the planet to make one revolution around the Sun. Thus, this means that Mercury orbits the Sun twice before it finishes one rotation around itself. This is because Mercury is really close to the Sun, so it can orbit around the Sun very fast. It also rotates around itself very slowly, which helps account for the odd ratio I provided. Finally, in terms of Earth days, Mercury orbits around the Sun every 88 days and rotates around itself every 176 days(thus the 2 to 1 ratio).
Layers of Mercury
Mercury, being a terrestrial planet, is dense. This is accounted for by the inner most layer of Mercury, the inner core, which is solid iron. The pressure from the rest of the planet(basically the weight of all this iron and the stuff on top of it) accounts for the solid behavior. After this comes a liquid outer core of similar composition. Then comes the mantle, which is separated from the outer core by a layer of solid iron. Explaining this is difficult, and I am not entirely sure why such a layer exists. Generally with less pressure comes a liquid form, and I have not come across explanations for this. The mantle of mercury is made of silicates(compounds made of silicon and oxygen) and is very thin, only 500 kilometers. Finally is the crust, which is considered the surface of mercury. This is discussed next.
Comparison of Earth’s interior to Mercury. Mercury is very small compared to Earth(about a tenth in mass) and has a significantly different interior).
Surface of Mercury
Mercury has a unique surface, but a great way to think of it is similar to the moon. There are many craters caused by impacts from different space objects like debris, asteroids, and planetesimals. The largest crater on mercury is Coloris Basin. The cracks of the smooth regions of mercury, rupes, are long cracks on the older surface of mercury caused by faults on Mercury(like fault lines on Earth where earthquakes happen). Final thing to know is the temperature changes of Mercury. As I will talk about next, Mercury does not have an atmosphere. Thus, temperature changes are extreme. It ranges between -300 to 800 degree Fahrenheit based on if it is day or night! Note that by extreme I mean the range of the temperatures, the change in temperature is not constantly fluctuating as the planet spins very slowly. It gradually decreases as night approaches.
The line through the middle is one of the rupes we discussed above. It is formed by a thrust fault(a fault like that of where an earthquake occurs).
Mercury’s Questionable Atmosphere
It is easiest to say that Mercury has no atmosphere. An atmosphere is the gases held by gravitation of a planet. Because of Mercury being so light, it does not have the mass to hold an atmosphere. Another issue is that Mercury is too close to the Sun. Remember the phenomena we talked about with the Sun? Those phenomena and just the flow of charged particles out of the sun produces what is called a solar wind. This wind blows away most of the “atmosphere” that the planet could hold onto. This means there is essentially nothing to consider as an atmosphere. However, there is still a little bit of gas held by the planet. This is mainly oxygen, sodium, and hydrogen. For reference, it is 10^34 times sparse than Earth’s atmosphere. That is Earth’s atmosphere divided by 1 with 34 zeroes in front of it.
For Educators
Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.
Thank you
Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!
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Above is an image of the different layers of the Sun.
The Sun is an above average sized star that holds our solar system in place. It is in the top ten percent, in terms of size, of all stars as most stars are red dwarves. A star is a ball of plasma(super-heated gas) that releases energy in the form of heat and light due to the fusion of gases(this is called fusion, it’s when atoms combine to form heavier ones due to the energy in the surroundings). Even though our Sun is 99% of the mass of the solar system, there are stars that are a thousand times larger(the star Betelgeuse is 700 times larger than our sun). The mass of our sun is what holds our solar system in an elliptical orbit, masses exert a force on each other called gravity(insert link to gravity post here). We do not know much about gravity but the link will lead to a post about what we believe happens.
Layers of the Sun
Just like Earth has different layers(Core, Mantle, Crust), the Sun has different layers. The innermost layer of the sun is the core. The pressure in the core of the sun is 260 billion atm(1 atmosphere, or atm, is the air pressure at sea level on Earth) and 15 million Kelvin(at this large scale, 1 Kelvin is approximately 1 Celsius). This is the layer where most of the hydrogen fusion happens, because the pressure(and thus energy) is immense. Every second the sun converts 700 million tons of hydrogen, forming 695 million tons of helium and 5 million tons of energy. To convert it, this is where Einstein’s classic E=mc^2, so 5 million tons of energy is 4,535,923,700kg(5 million tons as kg)*(3*10^8)^2=124,827,108,157,891,338,889 Watt*hours(so this number is the number of joules of energy expended in an hour, and it is gigantic) . For reference, your powerful home lightbulb is 100 Watts, so yes, the Sun produces a crazy amount of energy.
Above the core is the convective layer, this is where all the hydrogen moves up to because it is less dense than helium. This is called convective layer because the temperature gradient between this layer and the core causes the hydrogen to become less dense, float up, cool down, and then sink again.
Above this is the photosphere, which is thin enough for the light to escape. The top layer is the corona, which is thinner than the photosphere but much hotter than it. The corona stretches for many million kilometers. The solar wind is over a million km/hr
Surface Phenomenon
The first important thing to know about the surface of the Sun is that light is emitted from it. This light is what we see. You have heard that it takes 8 minutes for light to be made from the Sun and seen by us. This is only partly true. The distance from the Earth to the Sun is such that it takes 8 minutes for the light to reach us(the speed of light is 3*10^8 meters/second so multiply that by 480 seconds to get the total distance from Earth to Sun). However, the light we see is often more than 100 million years old! This is because of the fact that fusion, where light is produced, occurs in the core. So this light has to escape to the photosphere where it has some potential to escape. While in the core, it will just be circulated for many millions of years until it may escape.
That is how light comes to us, but there are a lot of cool phenomena that happen on the Sun also. These are invoked by the Sun having a significant magnetic field. This magnetic field is induced by a flow of electric charge in the Sun(a current can create a magnetic field, this is Ampere’s law). The flow of charge occurs in the convection zone, because of the high temperatures, not just hydrogen atoms but also free electrons get circulated. Related fact: The earth has a magnetic field for the same reason, but it is because of liquid metals flowing in the outer core that causes a flow of charge. This magnetic field on the sun causes many interesting phenomena on the sun.
Sun Spots
Sunspots are formed when the magnetic field doesn’t allow the plasma to return down the convective layer, causing it to dim on the surface. These sunspots appear in pairs(imagine a North pole and south pole of a magnet, sunspots occur in such a fashion often). Faculae are the bright rings around the sunspots formed by the concentrated magnetic field. These are very bright due to the heavy magnetic field causing significant circulation.
Solar Flares
A solar flare is when the magnetic field snaps, ejecting material into space. These often occur around sunspots because, as we discussed, the magnetic field around the sunspots is extremely prominent. A solar flare is like a slingshot of solar mass(the components of the Sun) being shot. When you hear of the risk of the Sun eliminating radio communications, flares are the reason
Solar Prominence
A solar prominence is when the sun’s magnetic field pushes the plasma out toward the surface. The difference between a flare and prominence is that a prominence does not eject anything. Rather, a large ring of plasma is formed on the surface of the Sun, directed by the magnetic field.
Coronal Mass Ejections
Coronal mass Ejections(or CMEs) is similar to a flare except its stronger and covers a wider area. These often occur when a solar prominence snaps, because the prominence holds a lot of energy it ejects much more mass. A CME in 1989 caused a total power outage in Quebec. In 2012, another CME occurred but in a different direction, saving the Earth from huge damage. These caused concern because the Earth’s atmosphere protects us from solar emissions, but a CME is so powerful that it gets free electrons through our atmosphere and can cause damage to a lot of our technology.
For Educators
After doing a short presentation about the concepts in the post, I would recommend doing a demonstration on the concept of convection. Check out this you tube video if you need inspiration for how to set one up(or would like to show it yourself). Teaching about the Sun is easiest using diagrams, so I would recommending making diagrams for the different layers of the Sun. Finally, teach about the phenomena by explaining their impact, like the examples I gave in the CME section. This is so students understand that the Sun is more than what we think of it, and that there is a lot to learn about it.
Thank you!
Thank you for reading about the Sun! If you have any comments, let me know at vijaypbharti01@gmail.com or in the comment section below.
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