Exoplanet
A planet orbiting a star outside our solar system.
Also: extrasolar planet
Definition
An exoplanet (extrasolar planet) is a planet that orbits a star other than the Sun. As of 2025, thousands of exoplanets have been confirmed using detection methods including the transit method (measuring stellar dimming as the planet passes in front) and radial velocity (measuring stellar wobble). Exoplanets range from Earth-sized rocky worlds to hot Jupiters, and some lie in the habitable zone of their stars where liquid water could exist.
Example
“The Kepler Space Telescope discovered thousands of exoplanets by detecting the tiny dips in starlight when planets transited their host stars; one notable find was Kepler-452b, a roughly Earth-sized planet in the habitable zone of a Sun-like star 1,400 light-years away.”
Synonyms
- extrasolar planet
- extra-solar planet
- alien planet
Antonyms / Opposites
- solar system planet
Images
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Related Terms
- Stellar Evolution
- Habitable Zone
- Spectroscopy
- Planetary Formation