Exoplanets, or planets orbiting stars other than the Sun, were first discovered in 1992 when two planets were found orbiting a pulsar. In 1995, the first exoplanet orbiting a main sequence star, 51 Pegasi, was discovered. As of 2022, over 5,000 exoplanets have been confirmed in over 4,000 planetary systems, with over 1,200 of those systems containing multiple planets. Current estimates suggest there is at least one planet per star in the Milky Way galaxy on average, though smaller planets are harder to detect than larger ones.
