... Adrastea and Metis lie within Jupiter's main ring and may be the source of material for the ring. ... Galileo Image of Adrastea . ... The longest dimension of Adrastea is approximately 20 kilometers (12 miles) across. ... These images, taken by Galileo's solid state imaging system between November 1996 and June 1997, provide the first ever "family portrait" of the four small, irregularly shaped moons that orbit Jupiter in the zone between the planet's ring and the larger Galilean satellites. ...