10 Rhea Moon Facts | Cool Facts about Rhea

There are many facts to learn about the moon Rhea. It orbits around the planet Saturn, and it’s Saturn’s second largest moon, which is why it is one of it’s more well known moons. Like many other moons of Saturn, it takes it’s name from one of the Titans of Greek mythology. Let’s learn a little bit more about the moon Rhea.


Rhea Moon Facts

  1. The radius of the moon Rhea is approximately 474.6 miles (763.8 km).
  2. This makes it less than half of the size of the Earth’s moon. However, it is still Saturn’s second largest moon, and the ninth largest moon overall.
  3. Rhea orbits Saturn at a distance of approximately 327504 miles (527,068km).
  4. Due to this close proximity from Saturn, it only takes Rhea 16 hours to complete one full orbit around the planet.
  5. Rhea takes it’s name from Rhea the Titan from Greek mythology. She was the wife of Cronus, the Greek equivalent of the Roman God, Saturn.
  6. Rhea was one of four moons discovered by Giovanni Cassini in 1672.
  7. Like many other moons of Saturn, Rhea has a very heavily cratered surface.
  8. The largest of these has a diameter of between 400 and 500km, and is named Tirawa.
  9. Rhea has an average surface temperature of approximately -174°c.
  10. Rhea has an atmosphere, which is made up primarily of oxygen. This comes from the water ice on it’s surface, which goes through a process called radiolysis to become oxygen.

One of the main ways that we’ve learned about Rhea is due to the Cassini Spacecraft images, which helps humans learn a great deal about Saturn and many of its moons. Because of the Saturn orbital period, it can take a long time for the planet to orbit the Sun.

Common Questions about Rhea

Where does Rhea get it’s name from?

Rhea takes it’s name from the Titaness daughter of Gaia and Uranus in Greek mythology. She’s also the wife of Saturn, and well.. his sister, too (yes, Greek mythology is full of weird stuff like this!). She is the mother of the Olympian Gods, most of whom you’ve probably already heard of (Zeus, Poseidon, Hades etc). Although Rhea was discovered back in the 1600s, it wasn’t actually named as such until 1847, and was named by John Herschel, the son of the man that actually discovered Uranus.

What is Rhea made of?

For many years, astronomers thought that Rhea was like many other moons and has a solid rock middle. However, in more recent years after discoveries from the Cassini-Huygens mission, we now believe that to be less rock, and more water ice. It’s estimated that this moon is more than 75% water ice, with the rest of it made up from rock.

What’s on Rhea’s surface?

As mentioned, Rhea has many craters on it’s surface, including one of the youngest craters of the Saturn moons called Inktomi, otherwise known as the Splat. This crater could be as young as 8 million years old, making it an interest for scientists. However, many of the other craters on Rhea’s surface are billions of years old.
Rhea also has an atmosphere, made up of oxygen and carbon dioxide.

What are Rhea’s orbit patterns?

It takes Rhea only 16 hours to go around Saturn once. This is because it is not that far from the planet itself, and orbits it quite closely. It is much closer to Saturn than other major moons like Titan and Hyperion, but not as close as Mimas and Enceladus.

Can I see Rhea with a telescope?

Although it isn’t always possible to see Rhea with a telescope, you can see Rhea with a high powered telescope sometimes. You may need a higher powered telescope to see Rhea, whereas even a cheaper telescope should be fine to see Saturn and it’s biggest moon, Titan.


Hopefully you’ve learned something interesting about the moon Rhea. It is the second largest of Saturn’s moons, and orbits it at a fairly average distance. It is well known to astronomers, with some referring to it as the “Snowball” moon, referring to it’s large water ice presence.

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