The Apollo missions were humankind’s first and so far only opportunity to walk on and explore another planetary body other than Earth. We know of eight planets and countless comets and asteroids in our solar system. The first confirmed detection of exoplanets — planets orbiting other stars — was made in 1992 when two planets were discovered winging around the pulsar PSR 1257+12 2,300 light years in the constellation Virgo. A third was found in the system two years later.
This artist’s view shows the hot Jupiter exoplanet 51 Pegasi b, which orbits a star about 50 light-years from Earth in the northern constellation of Pegasus. A hot Jupiter, the most common kind of exoplanet found, is a Jupiter-sized planet orbiting so close to its host sun it’s heated to high temperatures. M. Kornmesser/Nick Risinger (skysurvey.org)
A pulsar is a tiny, super-dense, city-sized star formed in the aftermath of a supernova explosion. Usually. In this case, it’s thought that two slightly larger stars called white dwarfs merged, with the planets forming from the disk of debris left over from the merger. By 1995 the first extrasolar planet around a sun-like star — 51 Pegasi — was found.