How Saturn got its rings?

Saturn is the third-largest celestial object in our Solar System and the sixth planet from the Sun. It is a gas giant comprising mostly hydrogen, helium, and some heavy metals at its core. These gas giants don’t have any solid surface. If you’d jump into the planet you’ll never hit anything but will be squished by the enormous pressure before reaching its core. Saturn gets its gold shades by the presence of ammonium crystals and other trace compounds.

Saturn weighs about 5.683 x 10^26 kg which is 95 times the mass of earth. Even though having a lot of mass its gravity is only 1.08 times that of earth. This huge difference is caused by its massive size. It is so massive that more than 700 earths can fit inside it and 9 earths in its diameter. Due to the volume-mass difference, it is very light that the whole planet can float on water. But the thing about Saturn which makes us excited is its gigantic rings.

Out of 8 planets (yes Pluto is not a planet), there are four gas giants and all of them have rings. Jupiter has 4 rings, Neptune has 5 and Uranus has 13. But none of these planets gets the attention in terms of rings compared to Saturn. As a matter of fact, Saturn only has 7 distinctive ring systems but due to their vast size and reflectivity, they get our most attention. The biggest rings are about 270,000 km in diameter and their thickness ranges from 30-300 feet. It is bright because of the ice and rock in contains which range from the size of dust particles to as big as a mountain. So let’s get to the question about how Saturn got its rings? To know about it we have to understand what Roche limit.

Roche Limit

It is a boundary between two celestial objects beyond which the smaller celestial object will be torn apart into fragments due to the tidal forces caused by the gravity between them. Roche Limit varies for different objects and depends on their densities, masses, and distance between them. We use different formulas for different types of materials (rigid, liquid). The Roche limit of the earth and moon system is 18,470 km above the earth’s surface. Moon orbits at a distance of 384,400 km from the earth’s surface. If in any case, the moon crosses the Roche limit the moon is torn apart into pieces and we would have rings. This also causes the debris to fall into the earth and cause mass extinction.

How Saturn Got its Rings?

Researchers found out the age of Saturn rings to be ranging from 100-10 million years. This big range of time is due to the various methods of calculation and the uncertainties of the data. We are still not sure about how they are formed but there are few concrete theories explaining their formation. It is considered that once an icy moon was orbiting close to the Roche limit of the Saturn and an Exoplanet hit that moon and pushed it into the Roche limit and it was shred and pieces have collided with each other and became even small. Debris from this event have fallen into Saturn and some of them are captured by its moons as most of its moons have ice on their surface.

Other theories suggest that the icy moon itself came close to Saturn and crossed the Roche limit. There is also a chance of the rings being formed since the beginning of the solar system.

Why Saturn’s rings orbit in the same plane?

The short answer is angular momentum. As the icy moon crossed the Saturn’s Roche limit it broke down into smaller fragments. But that moon had an angular momentum and it should be conserved. So all the particles are settled into the moon’s orbital plane by sharing the angular momentum of the moon.

Let me know other possible theories. Comment Below!

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