Dictionary

exoplanet en · NOUN

Pronunciation

• (Southern-England) audio
• /ˈɛksəʊˌplænɪt/ (Received-Pronunciation)
• /ˈɛksoʊˌplænət/ (General-American)

Etymology

Constructed from Ancient Greek: exo- (“outside; extrasolar”) + planet.

Meanings

1. A planet which exists outside Earth's solar system.
   • In the past two years, NASA’s Kepler Space Telescope has located nearly 3,000 exoplanet candidates ranging from sub-Earth-sized minions to gas giants that dwarf our own Jupiter. Their densities range from that of styrofoam to iron. 2013 May-June, Kevin Heng, “Why Does Nature Form Exoplanets Easily?”, in American Scientist, volume 101, number 3, archived from the original on 07 Aug 2013, page 184:
   • Astronomers have used two different exoplanet-detecting satellites to solve a cosmic mystery and reveal a rare family of six planets located about 100 light-years from Earth. […] Many exoplanets have been found orbiting dwarf stars that are much cooler and smaller than our sun, such as the famed TRAPPIST-1 system and its seven planets, announced in 2017. 2023 November 29, Ashley Strickland, “Astronomers discover nearby six-planet solar system with ‘pristine configuration’”, in CNN, archived from the original on 17 Feb 2026:
   • Now a team of researchers is offering what it contends is the strongest indication yet of extraterrestrial life, not in our solar system but on a massive planet, known as K2-18b, that orbits a star 120 light-years from Earth. A repeated analysis of the exoplanet’s atmosphere suggests an abundance of a molecule that on Earth has only one known source: living organisms such as marine algae. 2025 April 16, Carl Zimmer, “Astronomers Detect a Possible Signature of Life on a Distant Planet”, in The New York Times, →ISSN, →OCLC, archived from the original on 16 Apr 2025, Science:
   • In a first for astronomers studying worlds beyond our solar system, data from the Hubble Space Telescope have revealed water vapor in the atmosphere of an Earth-size planet. Although this exoplanet orbits a star that is smaller than our sun, it falls within what’s known as the star’s habitable zone, the range of orbital distances where it would be warm enough for liquid water to exist on a planet’s surface. 2019 September 11, Michael Greshko, “Water found on a potentially life-friendly alien planet”, in National Geographic, archived from the original on 13 Mar 2021:
   • More such announcements will likely come in the months to follow, as the first space observatory dedicated to hunting exoplanets, called COROT, begins full operation and researchers complete their calculations. 2007 September 1, Alexander Hellemans, “Dangling a COROT”, in Scientific American, volume 297, number 3, archived from the original on 06 Aug 2023, page 32:

Forms

Coordinates

exocomet · exomoon

Deriveds

exoatmospheric · exoplanetary · exoatmosphere · exoplanetology

Relateds

planetary system

Synonyms

extrasolar planet · exosolar planet

Translations (57)

bg екзоплане́та (planet outside Earth's solar system) · et eksoplaneet (planet outside Earth's solar system) · ja 系外惑星 (planet outside Earth's solar system) · gl exoplaneta (planet outside Earth's solar system) · cs exoplaneta (planet outside Earth's solar system) · ta புறக்கோள் (planet outside Earth's solar system) · kk күн жүйесі шегінен тыс ғаламшар (planet outside Earth's solar system) · cmn 系外行星 (planet outside Earth's solar system) · da eksoplanet (planet outside Earth's solar system) · eo ekzoplanedo (planet outside Earth's solar system) · fi eksoplaneetta (planet outside Earth's solar system) · el εξωπλανήτης (planet outside Earth's solar system) · gl planeta extrasolar (planet outside Earth's solar system) · pt planeta extrassolar (planet outside Earth's solar system) · lv citplanēta (planet outside Earth's solar system) · sk exoplanéta (planet outside Earth's solar system) · pt exoplaneta (planet outside Earth's solar system) · nl exoplaneet (planet outside Earth's solar system) · de Exoplanet (planet outside Earth's solar system) · hi बहिर्ग्रह (planet outside Earth's solar system) · lt egzoplaneta (planet outside Earth's solar system) · ko 외계 행성 (planet outside Earth's solar system) · sq ekzoplanet (planet outside Earth's solar system) · fr exoplanète (planet outside Earth's solar system) · vi hành tinh ngoài hệ Mặt Trời (planet outside Earth's solar system) · tr güneş dışı gezegen (planet outside Earth's solar system) · ja 太陽系外惑星 (planet outside Earth's solar system) · ko 계외 행성 (planet outside Earth's solar system) · sv exoplanet (planet outside Earth's solar system) · hu exobolygó (planet outside Earth's solar system) · az ekzoplanet (planet outside Earth's solar system) · es planeta extrasolar (planet outside Earth's solar system) · ga eiseapláinéad (planet outside Earth's solar system) · sa बहिर्ग्रह (planet outside Earth's solar system) · be экзаплянэ́та (planet outside Earth's solar system) · nrf exoplianète (planet outside Earth's solar system) · ro exoplanetă (planet outside Earth's solar system) · es exoplaneta (planet outside Earth's solar system) · pl egzoplaneta (planet outside Earth's solar system) · ko 태양계외 행성 (planet outside Earth's solar system) · ro planetă extrasolară (planet outside Earth's solar system) · ru экзопла́нета (planet outside Earth's solar system) · uk екзоплане́та (planet outside Earth's solar system) · ga pláinéad eachtarghréine (planet outside Earth's solar system) · de extrasolarer Planet (planet outside Earth's solar system) · ca exoplaneta (planet outside Earth's solar system) · sl eksoplanet (planet outside Earth's solar system) · be экзапла́нета (planet outside Earth's solar system) · sv extrasolär planet (planet outside Earth's solar system) · hy էկզոմոլորակ (planet outside Earth's solar system) · eo ekstersunsistema planedo (planet outside Earth's solar system) · pl planeta pozasłoneczna (planet outside Earth's solar system) · ru внесо́лнечная плане́та (planet outside Earth's solar system) · vi ngoại hành tinh (planet outside Earth's solar system) · cmn 太陽系外行星 /太阳系外行星 (planet outside Earth's solar system) · ar كَوْكَب خَارِج الْمَجْمُوعَة الشَّمْسِيَّة (planet outside Earth's solar system) · ka ეგზოპლანეტა (planet outside Earth's solar system)