Astronomy: Uranus

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Table of Contents

  1. Basic Facts
  2. Moons
  3. Atmosphere
  4. For Educators

Facts about Uranus

We are almost done with the planets, I hope your trip through the Solar System has been fun ๐Ÿ˜€

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!

Astronomy: Neptune

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Table of Contents

  1. Basic Facts
  2. Atmosphere
  3. For Educators

Facts about Neptune

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!

Astronomy: Saturn

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Table of Contents

  1. Basic Facts
  2. Rings of Saturn
  3. Atmosphere
  4. For Educators

Facts about Saturn

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!

Astronomy: Jupiter

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Table of Contents

  1. Basic Facts
  2. Moons
  3. Atmosphere
  4. For Educators

Facts about Jupiter

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 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!

Astronomy: Mars

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Table of Contents

  1. Basic Facts
  2. Surface Composition
  3. Atmosphere
  4. For Educators

Facts about Mars

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

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!

Astronomy: Earth

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Table of Contents

  1. Basic Facts
  2. Why Earth is not a Sphere
  3. Surface Composition
  4. Atmosphere
  5. For Educators

Earth: The Facts

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!

Astronomy: Mercury

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Picture of Mercury. Color enhanced beyond visible light to show variations we can’t see

Table of Contents

  1. Basic Facts
  2. Layers of Mercury
  3. Surface Composition
  4. Atmosphere?
  5. For Educators

Basic Facts of Mercury

Mercury orbits at 38 thousand kilometers from the Sun and weighs 3.285 ร— 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!

Astronomy: The Sun

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Above is an image of the different layers of the Sun.

Table of Contents

  1. General Facts
  2. Layers of the Sun
  3. Surface Phenomenona
  4. For Educators

General Facts

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.

The circles in the convection zone are the cycle of hydrogen atoms. The image was retrieved from http://burro.case.edu/Academics/Astr221/StarPhys/opacity.html

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.

Astronomy: The Moon

Before I talk about astronomy, I want to thank you for visiting and ask that if you enjoy what you just read or value our mission here at STEM Enterprises, please support our cause by donating here. Any donation will be used to provide our highly engaging and effective education(check out the website for what all we do) to students deprived of the opportunity to have a meaningful STEM education experience.

Table of Contents

Feel Free to Skip Ahead to Any of These:

Moon Composition

Phases of the Moon

For educators

Welcome to the Moon!

I hope you enjoyed your flight as we reached the Moon. The Moon(notice the capitalization, our moon is capitalized because it is special) is a 3500 kilometer(2200 miles approximately) wide rock floating about 240,000 kilometers from us.

What is the Moon made Of?

You probably have always wondered this, and no, it is not cheese ๐Ÿ™‚ Rather, the moon has very large, smooth surfaces called maria(mare singular) which means sea in latin(they truly look like large seas but just black). These are made of basaltic rock, which is the rock that forms from dried lava(just like obsidian from volcanoes). Since it is very glassy, it cooled quickly(more of a fun fact than a major topic, but feel free to read more into rocks to understand how this works). The other part of the moon, the highlands, is also basaltic, but made of slow cooling rocks(as such it is much more bumpy and uneven).

The dark parts are the maria and light parts are the highlands

Phases of the moon

the phases of the moon in a nice diagram

Now that we know what the moon is made of, we should talk about the other important concept of the moon, which is how the phases work. This is diagrammed above but is still very confusing, so do not expect this to come easy. But let’s get started!

The moon cycles through its phases in 30 days(29.5 to be a little more accurate). There are 8 phases total so each phase goes for 3-4 days. Before we talk about them, let’s understand why these phases happen. The half of the moon we say is always the same, this is because the moon is “tidally locked” as its rate of rotation(how long it takes to spin around itself) is equal to the rate of revolution(how long it takes to circle the Earth).

Since we always see the same half, based on where the moon is in reference to the Sun is how much of it we see lit up. The moon itself is extremely dark, the only reason it is seen as bright is because of the amount of sunlight that hits it. When you imagine this, please use the photo above and just remember that the Sun is always on the inside(where the sunlight arrows come from) because of the fact that we orbit the Sun once a year(thus we get the moon to cycle 12 times a year).

We start with the moon being between the Sun and Earth. This means the half of the moon we can not see is getting all the Sunlight, so the half we see is entirely dark. This is important, half of the moon always is lit! If you remember this, the rest will make more sense. This is called a new moon and happens at the beginning of the month(this is how a month was made when a new moon occurred in the past people established that as the start of the month). Now the moon starts to revolve around us while the sun stays in the same spot(for easier reference). The moon is now not directly between the Sun and Earth but is instead at an angle and the moon turns to face us(this revolution happens clockwise). Since it still faces us, a little bit of the moon “turned” to face the Sun, causing the right side to form a crescent of light. This is known as a waxing crescent, waxing because it is “growing” to full moon. This continues to happen until the whole right side becomes lit and is called the first quarter moon. But do not let the name mislead you, half the moon is lit up but we call it a quarter because we can only see a quarter as lit(the other lit quarter faces away from us). Now, this keeps progressing towards the full moon. The stage in between is called waxing(remember, growing) gibbous. I am not aware of the meaning of gibbous, but just remember it because it’s a silly-sounding word. We finally reach the point where the Earth is between the Sun and Moon(notice the order, Sun, Earth, then Moon). This means that the side of the Moon we can see is facing the Sun directly, and is called a full moon(only half is lit, but the full half we can see). This happens in the middle of the month(around the 15th generally). Now the Moon continues to revolve past this point, and as it revolves it turns away from the Sun so to speak, so we see a crescent of darkness form. Because most of the moon is still lit, it is still a gibbous moon but is a waning(shrinking) gibbous. This continues until quadrature or when the moon is at a 90-degree angle to the Earth and Sun(forms a right triangle). This means the third quarter has arrived, as the half of the moon we can see of has half of it lit up(the sunlight is coming from the left, and we look at it straight ahead.) Now past this point, the moon continues to revolve around us, and since it is locked to have the same half keep facing us, it will further turn away from the sun to form a waning crescent(waning because it is shrinking to new moon). Finally, at the beginning of the next month, the Moon returns to its original spot to become a new moon again.

I have discussed the main facts of the moon, the moon’s composition and the phases of the moon. There is obviously a lot more to learn but that is outside the scope of my general discussion, now that you have a starting point, just think of questions and try to answer them.

For Educators

Remember to do your 5-minute presentation on the above topics. These topics are probably the most important things for a general understanding of the moon. Students will struggle with the phases so I would recommend setting up a demonstration (or click this link for a virtual lab). I would recommend doing it in person so students get the 3D spatial understanding, this youtube video does a great job showing a potential experiment and you can be creative from there.

Thank you

Thank you for reading and learning the basics of the moon. If you want to learn more, I encourage you to explore other sources like youtube channels(crash course astronomy is where I learned a lot of my astronomy knowledge) or read books about the moon. Any questions or comments please contact me at vijaypbharti01@gmail.com

Astronomy: Before Space

Before I talk about astronomy, I want to thank you for visiting and ask that if you enjoy what you just read or value our mission here at STEM Enterprises, please support our cause by donating at here. Any donation will be used to provide our highly engaging and effective education(check out the website for what all we do) to students deprived of the opportunity to have a meaningful STEM education experience.

Image received from Earth Science by Tarbuck and Lutgens

The basics of astronomy start from our own planet, Earth. Our planet has been instrumental in understanding how outer space works so it is critical to get a simple understanding of our planet. Step 1 is the atmosphere. The atmosphere is essentially what we see when we look up, and it has multiple intersecting layers. The image above is really useful in understanding how the atmosphere works. I recommend reading the book in it’s caption to learn everything there is about Earth. Eventually I will have a blog on Earth Sciences also.

The atmosphere has 4(5 to some) main layers. The term layer is loosely used to describe a slice of the atmosphere that has similar properties. Layer 1 is the troposphere, so named because the phrase tropos means change(all of the layers end with sphere because sphere means realm, or region, that is why atmosphere is region of air(Atmos)). The change in troposphere means the fact that all weather occurs in the troposphere, so it is not constant. We see things like clouds in this region which goes vertically up 6.214 miles(10 kilometers). This is equivalent to 32809.92 feet, for perspective. When you are in a plane, you are in this region since planes fly at about 5-8 miles up.

After the troposhere comes the stratosphere, where stratos means layer. This shows that their is really not much happening in this layer except this is where the ozone layer you may have heard of exists. The ozone layer is a layer of trioxygen(3 oxygen) gas that prevents radiation from abundantly hitting the surface.

The next layer is the mesosphere, named such because it is the middle(meso) layer. In this layer, the air is very thin but the last layer to have mixed air(the gases like Nitrogen and Oxygen that make up the air are dispersed) but still exist. This is where you see meteors burn up, what we call shooting stars! This layer goes up to 80 kilometers. The top of the mesosphere is extremely cold(the coldest part of the atmosphere).

Finally we have the thermosphere(and some split the top of the thermosphere to the ionosphere, but I am not going to do that and discuss them as one). This layer starts at 90 kilometers and extends into outer space. We have nearly reached the stars! In this layer, air is extremely thin and separated based off different chemicals(why they split is a little complicated but has to do with reactions to UV radiation). This layer has extremely hot particles(1000 degree Celsius) but since the amount of particles are so little, it would not feel hot. This is the layer that produces the Auroras we have seen in photos(Northern and Southern Lights) because the UV radiation excites the ions in this sphere causing them to give off light as they relax. I’ll talk about how stuff like that works in a chemistry blog.

For Educators:

You can do a short presentation on the different layers of the atmosphere, but more importantly, teach students how air density/pressure decreases with altitude. Remember this is caused by having less particles of air at the higher altitudes. This can also be shown by being cold(if something is cold it means the particles are sparse and/or slow). For inspiration, check out this YouTube video

Thank you!

That is about it for this blog! We have launched off from Earth and have reached outer space. I will see you in the next blog. Contact me with comments at vijaypbharti01@gmail.com!