page_title: Exoplanet
section_title: Nomenclature
hierarchical_section_title: Exoplanet / Nomenclature
caption_attribution_description: English: The exoplanet HIP 65426b — the first to be seen by the SPHERE instrument on ESO’s Very Large Telescope. The image of the parent star has been removed from the image for clarity, and its position marked with a cross; the circle indicates the orbit of Neptune around the Sun on the same scale. The planet is clearly visible at the lower-left in this remarkable image.
context_page_description: 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 August 2020, there are 4,301 confirmed exoplanets in 3,176 systems, with 703 systems having more than one planet.
  There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like stars have an "Earth-sized" planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.
context_section_description: The convention for designating exoplanets is an extension of the system used for designating multiple-star systems as adopted by the International Astronomical Union (IAU). For exoplanets orbiting a single star, the IAU designation is formed by taking the designated or proper name of its parent star, and adding a lower case letter. Letters are given in order of each planet's discovery around the parent star, so that the first planet discovered in a system is designated "b" (the parent star is considered to be "a") and later planets are given subsequent letters. If several planets in the same system are discovered at the same time, the closest one to the star gets the next letter, followed by the other planets in order of orbital size. A provisional IAU-sanctioned standard exists to accommodate the designation of circumbinary planets. A limited number of exoplanets have IAU-sanctioned proper names. Other naming systems exist.
caption: Exoplanet HIP 65426b is the first discovered planet around star HIP 65426.[38]
exif: {"Image ImageDescription": "The exoplanet HIP 65426b \u2014 the first to be seen by the SPHERE instrument on ESO\u2019s Very Large Telescope. The image of the parent star has been removed from the image for clarity, and its position marked with a cross; the circle indicates the orbit of Neptune around the Sun on the same scale. The planet is clearly visible at the lower-left in this remarkable image."}