Basics: Planet Saturn
Main Image Credit: NASA, ESA, A. Simon (GSFC), M.H. Wong (University of California, Berkeley) and the OPAL Team, Published: September 12, 2019
Saturn is named after the Roman god of agriculture and wealth, and was considered father of the king of Gods, Jupiter. The 6th planet from the Sun, Saturn, is the second largest in the solar system. It is similar to Jupiter in that is a gas giant with an “atmosphere” of mostly hydrogen and helium. Like Jupiter, this planet has materials similar to a star.
Saturn also has an impressive amount of moons. At the time of writing this article, 53 are confirmed and 29 are in need of further evidence. Saturn’s moons are some of the most interesting. Titan, the second largest known moon, is the only moon known to have a thick atmosphere. Enceladus is known to spray jets of water.
The first 4 planets from the Sun are all fairly close to each other and well within 230 million km from the Sun. Jupiter is over 3.5 times further, and then Saturn is almost twice as far from the sun as Jupiter. One of the easiest ways to compare is with the use of the AU measurement. It stands for “Astronomical Unit”, and it is easy because earth is considered 1 AU from the Sun. In this way we can see that Saturn is 9.5 AU from the Sun.
Regardless of distance, Saturn can still be seen as a bright point of light in the sky. It can be seen with the naked eye but is much more spectacular with a telescope. In this way the rings can be viewed.
Due to Saturn being a gas giant there is not technically any known surface. It is believed there could be a solid core, but it is unknown at this time at what point down through the planet it is.
The surface does not seem to have as well defined lines and colours as Jupiter. On closer inspection those typical gas giant lines are visible. Unlike Jupiter, Saturn has a somewhat milky colour to its surface. The following video seems more suited to kids, but it is a fun watch:
Saturn is about 9 times wider than Earth. It is noted that Saturn is not completely spheroid though, it is oblate. This means that it is flattened at the poles. Even though Saturn does not rotate as fast as Jupiter, it is still flatter. In fact, Saturn is the most oblate planet in our system.
Being a gas giant, Saturn has a very deep atmosphere, making it difficult to determine its exact size. Although not as clearly defined from space as Jupiter, bands of activity can be seen. The atmosphere is very stormy. These clouds cover its lower layers.
The wind speeds can get as high as 1,600 feet per second (500 meters per second) in the upper atmosphere. This is noted especially in the equator region. The pressure is so high that gases are squeezed into a liquid form.
One highly intriguing shape, that is literally a hexagon, can be found at the North Pole. It is unique, and is not observed in any other solar system body. It spans approximately 20000 miles across (30000 km), and has an intense rotating storm at the centre.
Rings of Saturn
Saturn is not the only planet in our solar system to have rings. It is however the one with the most pronounced, and visible ring systems. Jupiter’s rings are really quite difficult to see in comparison. Amateur telescopes will be no good for Jupiter rings (the rings were only discovered with very detailed viewing of the planet close up). Saturn on the other hand... you could quite possibly see those rings with binoculars!
As mentioned in the next section, you will notice certain gaps in the rings. These are made by (shepherd) moons that sit at certain points within the rings. Note that the rings are extremely thin. This means that at certain points, looking at Saturn, you would likely see nothing. They are typically a few metres/ feet wide; some parts of the rings may be several km though. Put that into the context of the planet being 9 times wider than Earth, it is clear to see they are very thin indeed.
The rings exist for a number of different theoretical reasons. If we take mars as an example; Phobos is the closest to its parent planet of any other moon in the system. It is theorized that once the moon gets close enough it will get ripped apart, and then create a ring system around the planet. Another way is for an object like an asteroid to hit a moon. The ensuing debris can form ring materials. For further information see:
Moons of Saturn
Like Jupiter, Saturn has a wide array of very interesting moons. It is host to the second largest moon in the solar system, Titan. What is intriguing about Saturn, in comparison to Jupiter, is the amount of large sized moons. When speaking of Jupiter, most people mention the 4 Galilean moons. After those 4 moons, the rest are rather tiny, more like rocks. Saturn has a larger number of sizable moons (that are large enough to be spheres), although most are quite a bit smaller than Jupiter’s 4 main ones.
There are certain categorizations of the moons. One that is notable is a shepherd moon. A shepherd moon is one that sits within the ring system. It creates a gap due to the gravitational force of the moon.
The following highlight the 7 large moons of Saturn. They are in the order of closest to the planet:
- Mimas: Although quite a few small moons are closer to Saturn, Mimas is the closest significant sized moon. Its most significant feature is one crater, named after William Herschel, who discovered the moon in 1789. It is believed to be the smallest known body that is rounded through self gravitation.
- Enceladus: This moon garners much attention due to its geologically active state, and known liquid water content. This water can be seen being ejected from the planet surface as vapour. It has been magnificently captured by the Cassini probe. It is considered likely to have microbial life. The surface is extremely bright and reflective.
- Tethys: This is a mainly icy body. It is also very bright like Enceladus. It is said to have a certain amount of dark material present on the surface too, as well as the icy layer.
- Dione: This is another icy type moon. One intriguing feature is its odd looking dark area. This could be due to magnetospheric radiation.
- Rhea: This is the second largest of Saturn and 9th largest in the solar system. It is another icy body with low density.
- Titan: This is one of the most fascinating objects in the solar system! It is possibly a contender for the most intriguing moon for a number of reasons. It is the only moon with a dense atmosphere. Its colour is very distinctive. It looks the way it does for similar reasons to Venus; the atmosphere obscures its surface. That alone makes it mysterious and worthy of attention.
- Iapetus: Note that the first letter is “i”, not “L” (one of the unfortunate letters of the English alphabet). This is the third largest moon of Saturn. It is known for its odd colour pattern; in other words, its dark patch. It is way further out than Titan; it is almost 3 times as far out.
Images of Saturn and its Moons:
The last image from Cassini (a teary eyed moment not long before it crashed into Saturn). Source: NASA/JPL-Caltech/SSI, Published: November 21, 2017:
The peculiar hexagon on Saturn's North pole, NASA/JPL-Caltech/Space Science Institute, Published: May 08, 2017:
5 moons captured by Cassini, with Saturn rings clearly in background. NASA/JPL-Caltech/Space Science Institute, Published: July 30, 2018: