PLANETS & MOONS A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site Adrastea The second-closest moon of Jupiter, moving just one Jovian radius above Jupiter's cloud tops. Adrastea is extremely small and irregular in shape. Like its inner neighbor, Metis, it orbits faster than Jupiter spins on its axis, a situation that results in orbital instability and will eventually cause Adrastea to spiral into Jupiter's atmosphere. Adrastea is a shepherd moon of Jupiter's main ring and, together with Metis, appears to be the source of the material making up this ring. discovery 1979, D. Jewitt and E. Danielson based on Voyager data semimajor axis 128,690 km (79,980 miles) diameter 26 × 20 × 16 km (16 × 12 × 9 miles) mean density 3.0 g/cm3 escape velocity 0.011 km/s (40 km/h, 25 mph) orbital period 0.298 day (7 h 9 min) orbital eccentricity 0.002 orbital inclination 0.000° visual albedo 0.10 Related entry    • Jupiter, moons Related category    • PLANETS AND MOONS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP