exoplaneter

Exoplaneter is a term occasionally used to denote a planet located outside the solar system. In mainstream astronomy the standard term is exoplanet; exoplaneter appears mainly in speculative, educational, or literary contexts and is not widely adopted in scientific literature.

An exoplaneter or exoplanet orbits a star other than the Sun. They vary greatly in size, composition, and orbital configuration, from gas giants larger than Jupiter to rocky worlds smaller than Earth. Some reside in the habitable zone where liquid water could exist, while others experience extreme radiation, eccentric orbits, or strong tidal forces. The study of exoplaneters aims to understand planetary formation, system architectures, and the diversity of planetary environments beyond our own solar system.

Detection methods include transit photometry, which monitors periodic dimming as a planet passes in front of its star; radial velocity, which detects shifts in the star’s spectrum due to gravitational tug by the planet; direct imaging, which attempts to capture light from the planet itself; gravitational microlensing; and astrometry. Each method provides different information, such as orbital period, minimum mass, and, in some cases, atmospheric composition when combined with spectroscopy.

As of recent decades, thousands of exoplaneters have been confirmed, revealing a broad array of worlds—from hot Jupiters to temperate super-Earths. Space missions and ground-based surveys continue to refine measurements and extend atmospheric studies, offering insights into planet formation and potential habitability across the galaxy.

See also: exoplanet, planetary habitability, transit method, radial velocity method.