Io

Fact about Io

• Io is the most volcanically active body in the Solar System.

How Big is Io?

Io is 3642.6 km, or 0.28 Earths wide.

What is Io surface like?

Unlike most moons, Io has a "young" surface. Because there is so much volcanic activity, the surface is almost free of craters.

In addition to volcanoes, Io also has many mountains, lakes of molten sulfur, calderas, and flows of molten sulfur or silicate hundreds of kilometers long. The colour of the surface is due to sulfur and its various compounds.

How Long Is a Day on Io?

Io takes about 1 and three-quarters of a day to complete one rotation.

Who is Io Named After?

Io is named after one of Zeus' many lovers.

How was Io discovered?

Io was discovered by both Simon Marius and Galileo Galilei. It was found on Janurary 7, 1610.