... Discovery Image: Comet SOHO (1998 J1) . ... Staring at the Sun from a vantage point in space (Kids, don't try this at home!), the Solar and Heliospheric Observatory (SOHO) has enabled the discovery of much about our closest star. ... A human first set foot on another world on July 20, 1969. ... Our Solar System from Voyager . ... The most distant of Jupiter's Galilean Moons, Callisto shows the highest density of impact craters in the Solar System, but harbors no volcanoes or even any large mountains...