Discovery and exploration of the Solar System Earth to be orbited by an artificial satellite ("Luna 10"), followed by Mars in 1971 ("Mariner 9"), Venus in 1975 ("Venera 9"), Jupiter in 1995 ("Galileo"), the asteroid 433 Eros in 2000 ("NEAR Shoemaker"), Saturn in 2004 ("Cassini–Huygens"), and Mercury and Vesta in 2011 ("MESSENGER" and "Dawn" respectively). "Dawn" is orbiting the asteroid–dwarf planet Ceres as of 2015. The first probe to land on another Solar System body was the Soviet "Luna 2" probe, which impacted the Moon in 1959. Since then, increasingly distant planets have been reached, with probes landing on or impacting the surfaces of Venus in 1966
Solar System Solar System The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, such as the five dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury. The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with