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!