The second largest of the inner satellites of Jupiter, Thebe orbits within the outer edge of the Thebe gossamer ring that is formed from dust ejected from its surface. It is irregularly shaped and reddish in colour, and is thought like Amalthea to consist of porous water ice with unknown amounts of other materials. Its surface features include large craters and high mountains—some of them are comparable to the size of the moon itself.
Thebe was discovered by Stephen P. Synnott in images from the Voyager 1 space probe taken on March 5, 1979, and was initially given the provisional designation S/1979 J 2. In 1983 it was officially named after the mythological nymphThebe who was a lover of Zeus—the Greek equivalent of Jupiter.
After its discovery by Voyager 1, Thebe was photographed by the Voyager 2 space probe in 1979. However, before the Galileo spacecraft arrived at Jupiter, knowledge about it was extremely limited. Galileo imaged almost all of the surface of Thebe and helped clarify its composition.