Just to make sure you understand which planet I am talking about, Saturn is the big one with the rings. You might probably remember Saturn like that, but I am about to present it to you in a deeper way. With an estimated mass of 5.7 x 10^28, which is basically 568,319,000,000,000,000 billion kg, Saturn is the second largest planet in our Solar System. Even though it is ginormous, it is the only planet with an average density that is less than water. Such as Jupiter, it spins quickly on its own axis, meaning that a day inside this planet is approximately 10h 39 minutes, which is why if you observe it in detailed models or pictures, you can see some fading stripes form. As a result, winds in the upper atmosphere reach 500 meters per second. Another similarity it has with Jupiter is the common occurrence of hurricanes and vortexes. Saturn’s hexagon for example (located in its north pole) is a massive hurricane with an eye 50 times larger than an average hurricane on Earth. It extends 945 km from the eye of the storm. The hexagonal shape of the whirlwind is due to an external pressure created by smaller storms pushing the bigger ones in an attempt to coexist, which makes the bigger ones lose their shape and develop this polygonal shape. Back to completing the previous information about the basic aspects of the planet, It takes for this giant 29 Earth years to give a whole lap to the sun, which in other words is that its orbital sun period equals 29 years. Its distance from the sun is about 1,482,623,940 km or 9.57 AU. From this distance, it takes sunlight 80 minutes to travel from the sun to the planet. It tilts on its axis by 26,73°, similar to Earth’s which is 23,5°. With a tilt so similar, scientists can infer that Saturn also has seasons, making it possible that the winds on Saturn are five times as fast as the ones found in Jupiter during fall or winter. The mean temperature is -138°C, but the specific temperature per season is currently unknown. While the biggest planet in our SS has just three rings, on this planet we can find a total of seven rings made out of billions of icy grains and rock coated with dust and other materials. These are thought to be pieces of asteroids, comets, and shattered moons that were broken by the gravitational pull of this immense planet. The rings are labeled with the letter of the alphabet in the order they were discovered. The size of the components of the rings can vary from small particles to huge fragments as big as mountains, which is why it is very difficult to verify the quantity of moons the planet has. Until this day, there are 53 confirmed moons and 29 that are awaiting approval, but it is believed that Saturn could have up to 150 satellites orbiting it. Some of its moons act as magnets that prevent the rings from spreading out. The most common moons of this gas giant are Enceladus, Dione, Hyperion, Iapetus, Mimas, Rhea, Titan and Tethys; in this article I am only going to talk about Enceladus and Titan for the sake of conciseness. First, let’s start with Titan. After Jupiter’s Ganymede, Titan is the second largest moon in the whole SS, it is even bigger than Venus. Just like our moon, Titan does not spin on its own axis, it just shows Saturn the same face all the time, which is why its length of the day is the same as the time it takes Titan to give one lap to Saturn: 15 days with 22 hours. Like Europa, Titan is an ice moon, though in this one it is proven by the Cassini spacecraft that there is an ocean above a water ice crust that is approximately 55-80 km thick. Here is a very important detail: do you remember when I talked about the three ingredients for life? Well, Titan has an even more unique feature than Europa, an atmosphere. Just like Earth, Titan has a thick atmosphere made of mostly nitrogen. About 95% of it is composed of Nitrogen, and it is estimated that 5% of it is Methane, but this atmosphere also includes other carbon-rich compounds that are essential for the chemistry, one of the ingredients for life. When Ultraviolet rays from the sun and high energy particles accelerated by Saturn's magnetic field split the methane and nitrogen molecules, the remaining pieces recombine to form new compounds such as oxygen and other ones that are important for the development of life. This act of breaking down and recycling parts of molecules creates a kind of fog in the atmosphere that gives the moon its orange appearance and makes it more difficult to see the ice crust, the surface of the planet. As I previously mentioned, below the ice crust relies a water ocean rich in salt and gasses essential for some microorganisms like ammonia, which means that life could potentially exist in this ocean. Unlike Europa, life could also survive on the surface due to big rivers and lakes of liquid methane and ethane found on it, but this means we could find life in a totally different way to the one we know now. However, until now no other moon seems to be more prominent to be habitable than Enceladus. This fantastic moon orbits Saturn at a distance of 238,000 km from Saturn, between the orbit of the moons Mimas and Tethys. Like Titan, it shows the same face to Saturn, which is why a day inside this moon equals 32.9 Earth hours, and it also has the same orbital period around Saturn. This is the most reflective world in the whole SS. As a result, it reflects the sunlight, causing the surface temperature to be 201°C below zero, but it still produces heat in a similar way to Europa. Enceladus is trapped in a stage where two or more moons line up with their parent planet at regular intervals and interact gravitationally with each other. This is also called orbital resonance. In this case, Dione, another moon of Saturn that is larger, is the one that maintains Enceladus in the orbital resonance, provoking that it develops an elliptical orbit in which in periapsis to Saturn becomes oval shaped while in apoapsis it becomes more spherical, resulting in internal friction that traduces into heat. The moon’s clean white color is due to jets of icy water particles and gas gush from the moon’s surface. These materials are ejected into space (meaning that the moon ejects water samples to space) or it gets trapped in the atmosphere and is transformed into snow that descends and covers the surface of the moon, giving it its signature white color. Some of the materials ejected into space sumministrate material to the E ring of Saturn. The water jets come from “the tiger stripes”, which are warm fractures on the satellite's crust. This strong plume includes several gasses such as water vapor, carbon dioxide, methane, and a little ammonia, and they could be ejecting either nitrogen or carbon monoxide, along with salts and silica. In the E ring we can find some particular nanograins of silica in this ring, which is a grain that can only be created by the interaction of water and rocks in a temperature of 90°C, suggesting that this water ejections come from a body of hot water above the ice layer, and that this body of water must be big and deep… an ocean. With this ocean, the correct chemistry, and the internal heat generated at the core of the moon, Enceladus could be one of the most promising worlds in our solar system that could host life!  

 

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Urrutia, D. E. (2021, August 1). Look up! Saturn shines bright, shows off rings as it reaches opposition. Space.Com. Retrieved February 10, 2022, from https://www.space.com/saturn-opposition-2021-skywatching#:%7E:text=2

 

The Nine Planets. (2020, September 29). How Many Planets are in our Solar System? | Facts & Amount. Retrieved February 12, 2022, from https://nineplanets.org/questions/how-many-planets-are-in-our-solar-system/

 

Europa. (2021, November 4). NASA Solar System Exploration. Retrieved February 10, 2022, from https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/