Rhea
Where is Rhea?
Look south, about 40° up at 00:49 in Cetus.
- Rises
- 18:34
- Highest
- 00:47
- Sets
- 06:59
- Best after dark
- 00:49 · 40°
Can I see Rhea tonight?
Rhea always stays within a small fraction of a degree of Saturn, so its position tonight is Saturn’s position.
From London tonight, Rhea is above the horizon all night. It’s highest after dark at 00:49, in the south at 40°.
This is position and timing only: clouds, haze and light pollution aren’t included.
What does Rhea look like?
Eyes
Not visible.
Binoculars
Not visible.
Telescope
Around magnitude 9.7. A telescope of about 100–150 mm (4–6 inches) shows it as a faint point close to Saturn, a little beyond the edge of the rings.
About Rhea
Rhea is Saturn’s second-largest moon, about 1,500 km across. It is a cold, airless ball of ice and rock, heavily cratered across its surface.
It was discovered by Giovanni Cassini in 1672. The Cassini spacecraft, named after him, flew past Rhea several times and found bright, wispy cliffs of ice on one side.
Rhea orbits closer to Saturn than Titan does, so it stays near the planet in a telescope and takes careful looking to pick out.
Rhea is made mostly of water ice with a smaller amount of rock, and its surface is extremely cold, around −200 °C. In 2010, Cassini detected a very thin exosphere of oxygen and carbon dioxide around it. A possible ring around Rhea was proposed in 2008, but later observations did not confirm it.
Rhea orbits Saturn every 4.5 days, so its position changes noticeably from night to night. It is about three times fainter than Titan, which makes it a good next step once you have found Titan.
Saturn and its moons
Questions
What telescope do I need for Rhea?
How is Rhea different from Titan?
Sources: SkyMate; star chart: Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences