Formation and evolution of the Solar System have been forged from the remnants in less violent collisions. Moons around some asteroids currently can only be explained as consolidations of material flung away from the parent object without enough energy to entirely escape its gravity. Moons have come to exist around most planets and many other Solar System bodies. These natural satellites originated by one of three possible mechanisms: Jupiter and Saturn have several large moons, such as Io, Europa, Ganymede and Titan, which may have originated from discs around each giant planet in much the same way that the planets formed from the disc around the Sun.
Sagan Planet Walk Sagan Planet Walk The Sciencenter's Sagan Planet Walk is a walkable scale model of the Solar System, located in Ithaca, New York. The model scales the entire Solar System—both planet size and distances between them—down to one five billionth of its actual size. Consisting of eleven obelisks situated along a path through the streets of downtown Ithaca, the Planet Walk leads from the Sun at Center Ithaca to Pluto at the Ithaca Sciencenter. The exhibition was originally created in 1997 in memory of Ithaca resident and Cornell Professor Carl Sagan. In 2012, the model was expanded to include a representation