This is a timeline of Solar System exploration ordered by date of

spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, ...

launch. It includes: *All spacecraft that have left Earth orbit for the purposes of Solar System exploration (or were launched with that intention but failed), including

lunar probe The physical exploration of the Moon began when ''Luna 2'', a space probe launched by the Soviet Union, made an impact on the surface of the Moon on September 14, 1959. Prior to that the only available means of exploration had been observat ...

s. *A small number of pioneering or notable Earth-orbiting craft. It does ''not'' include: *Centuries of terrestrial telescopic observation. *The great majority of Earth-orbiting satellites. *

Space probe A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; o ...

s leaving Earth orbit that are not concerned with Solar System exploration (such as

space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launch ...

s targeted at distant galaxies,

cosmic background radiation Cosmic background radiation is electromagnetic radiation from the Big Bang. The origin of this radiation depends on the region of the spectrum that is observed. One component is the cosmic microwave background. This component is redshifted ph ...

observatories, and so on). *Probes that failed at launch. The dates listed are launch dates, but the achievements noted may have occurred some time laterin some cases, a considerable time later (for example, ''

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', ...

'', launched 20 August 1977, did not reach Neptune until 1989).