Jupiter, Uranus and Neptune – precisely the three planets most similar to Saturn. The similarities between them are as follows: they are all giants compared to the other planets in our solar system; all are formed basically by gas; and all have a large number of satellites. The trio’s rings were less well known than Saturn’s because they were more tenuous, composed mostly of microscopic particles. For this reason, those of Jupiter were only discovered in 1979, by the instruments of the American spacecraft Voyager, and those of Uranus, in 1977. Those of Neptune, in turn, which science imagined were arcs (rings in half), they only appeared in full in 1989, detected by Voyager 2. For comparison, Saturn’s rings had already been observed by the Italian astronomer Galileo Galilei (1564-1642), who compared them to ears when he saw them for the first time with his telescope .
The most incredible thing is that, even after all these centuries, these formations still keep mysteries about their origin. The reason they exist, however, is well known. Planetary rings are formed by dust and small rocks that cannot unite, through gravity, to form a single satellite – which would be the most natural process. This is because such fragments are extremely close to the planets, within a distance known as the Roche Limit. In this domain – whose borders vary according to the dimensions of the star -, the planet’s gravitational force does not allow the rocks to coalesce. This force is so powerful that it can break celestial bodies the size of a satellite without, however, swallowing them inside the planet.
It is even believed that the rings may have arisen in this way: from the collapse of one or more satellites that would have penetrated the Roche Limit of these giant and gaseous stars. Another theory says they formed along with the planets themselves. In that case, the rings would just be satellites that couldn’t be born.
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– Why do the planets rotate?
– What is the weight of a person on other planets?
decisive border Distance from the planet defines formation of rings or moons
When the particles that revolve around a planet are between it and a border called the Roche Limit, the gravitational force of the star does not allow the bodies to unite. There, they tend to form rings
If the particles are outside the Roche Limit, they will be able to pull together by their own gravitational force. This is how satellites are born