... Rhea: Saturn's Second Largest Moon . ... Rhea is the second largest moon of Saturn, behind Titan, and the largest without an atmosphere. ... Sun, Moon, Hot Air Balloon . ... Anticipating the celestial shadow play of a solar eclipse, sky gazers across Germany watched the Sun rise on May 31. ... If the Moon's apparent diameter is not quite large enough to cover the Sun during a solar eclipse, an annular eclipse can be the result -- a spectacle of silhouetted Moon surrounded by a solar "ring of fire". ...