Adrastea (moon) No surface details of Adrastea are known, due to the low resolution of available images. Adrastea is the smallest and second-closest member of the inner Jovian satellite family. It orbits Jupiter at a radius of about 129,000 km (1.806 Jupiter radii) at the exterior edge of the planet's Main Ring. Adrastea is one of only three moons in the Solar System known to orbit its planet in less than the length of that planet's day—the other two being Jupiter's innermost moon Metis, and Mars' moon Phobos. The orbit has very small eccentricity and inclination—around 0.0015 and 0.03°, respectively. Inclination is
Orbit of the Moon Orbit of the Moon The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in about 27.32 days (a sidereal month) and one revolution relative to the Sun in about 29.53 days (a synodic month). Earth and the Moon orbit about their barycenter (common center of mass), which lies about from Earth's center (about of the radius of Earth). On average, the distance to the Moon is about from Earth's center, which corresponds to about 60 Earth radii. With a mean orbital velocity of 1.022 km/s (0.635 miles/s), the Moon covers a distance approximately