Io

Io is the name of one of the moons of Jupiter and is the innermost of the four Galilean moons. Io has a diameter of 3,642 kilometers and a surface area of 41,910,000 km2. It's mass is 8.9319×1022 kg, 0.015 that of Earth's. It's name is taken from the Greek mythological figure Io, who was a priestess of the goddess Hera and living in Argos. Io has also been referred to as Jupiter I, or, the First Moon of Jupiter.