An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such. The first confirmation of detection occurred in 1992. This was followed by the confirmation of a different planet, originally detected in 1988. As of 1 April 2021, there are 4,704 confirmed exoplanets in 3,478 systems, with 770 systems having more than one planet.
