This little-known world reminds us of the photos of our satellite. This is Rhea - Saturn's second-largest moon and also the ninth in our entire solar system. It is one of the earliest discovered planetary moons.

Artist's conception of Rhean rings

By NASA/JPL/JHUAPL link [Public domain]

The satellite was discovered in December 1672. This was done by Italian astronomer Giovania Cassini. Its name comes from Greek mythology. Rhea is an ice moon. Its construction isn't known to us. Suppositions point to a thin outer layer of pure ice, and in the middle is a mixture of ice and rocks. The Cassini spacecraft in 2010 revealed the existence of a very scarce atmosphere surrounding the satellite. Oxygen and carbon dioxide were found in its composition. It is about 5 billion times less frequent than the Earth's atmosphere. The satellite orbits Saturn in an orbit about 1 million kilometers in diameter. The full circle of the planet takes four and a half days for the moon. Like our earthly Moon, Rhea is always turned one side toward Saturn. In the past, there were hypotheses that there is a ring around Rock and ice around Rhea, but it could not be confirmed.

Photo from Cassini spacecraft - Rhea at approximately 2,348 miles (3,778 kilometers) away

By NASA/JPL-Caltech/Space Science Institute link [Public domain]

The Rhea diameter is 1528 kilometers, which is more than half the size of our silver globe. The density of the satellite is about 1.24 kg / dm3. The surface of the moon covers most of the sunlight received. The hemisphere that is always turned to Saturn is noticeably brighter than the other. Impact craters cover most of the Rhea surface. The shape of the craters is similar for all ice moons and is different from those on our Moon or on the planet Mercury. The most famous crater of this satellite is Inktomi. It has a diameter of 47.2 km. The temperatures at Rhea are very low and range from -220 degrees Celsius on the side not illuminated by the sun to -174 on the side exposed to its rays.

Photo from Cassini spacecraft - Rhea at approximately 174,181 miles (280,317 kilometers) away

By NASA/JPL/Space Science Institute link [Public domain]

The first photos of Rhea were sent by the Voyager 1 and Voyager 2 probes, but in fact most of the knowledge about this satellite is due to the Cassini probe. It was she who took accurate photos of the moon, flitting a few times close to its surface. The closest probe was in January 2011, when it flew 69 kilometers above the surface of Rhea. And what do you think about this distant and unknown world? At first glance, it's our Silver Globe, but it's not him.

Greetings to lovers of Astronomy!

Sources:

Rhea
Moons of Saturn
List of natural satellites
and my knowledge...

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