An exoplanet (, ) or extrasolar planet is a planet outside our solar system. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such. However, the first scientific detection of an exoplanet was in 1988, although it was not accepted as an exoplanet until later. The first confirmed detection occurred in 1992. As of 29 August 2018, there are 3,823 confirmed planets in 2,860 systems, with 632 systems having more than one planet.