What does extrasolar mean?
"Extrasolar" is an adjective meaning located or occurring outside the solar system — beyond the reach of the Sun's gravitational domain. It is used almost exclusively in astronomy and space science, most frequently to describe planets detected around other stars: an "extrasolar planet" orbits any star other than our Sun. The word combines the Latin prefix "extra-" (outside) with "solar" (of the Sun), and emerged into widespread use during the late twentieth century as observational techniques matured and discoveries accelerated. While astronomers increasingly favor the compact term "exoplanet," "extrasolar" persists as the more formal adjective in scientific papers, journalism, and educational writing. It carries no figurative or informal connotations; it remains a precise technical descriptor. Related but distinct terms include "interstellar" (between stars within the galaxy) and "extraterrestrial" (beyond Earth generally), making "extrasolar" the narrowest and most specific of these spatial descriptors.
adjectiveSituated or occurring outside the solar system; belonging to or originating from a star system other than the Sun's.
- Relating to or situated outside the solar system, especially describing planets that orbit stars other than the Sun.
"Astronomers announced the discovery of an extrasolar planet orbiting a nearby red dwarf."
"The Kepler telescope identified thousands of extrasolar candidates before its retirement."
"Scientists debate whether extrasolar moons could ever be directly imaged with current technology."
The first confirmed extrasolar planet was spotted around a pulsar in 1992 — and it wasn't found by looking for light, but by listening to the timing of dead-star pulses.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of extrasolar
The word "extrasolar" derives from the Latin prefix "extra-", meaning "outside" or "beyond", combined with "solar", from Latin "solaris", relating to the sun (Latin "sol"). It formed on the model of earlier compounds such as "extraterrestrial". The term entered English scientific usage in the twentieth century, becoming widespread after the first confirmed detections of planets around other stars in the 1990s. It shares its roots with words such as "solstice", "parasol", and "solarium", all ultimately tracing back to the Proto-Indo-European root *sóh₂wl̥, meaning "sun".
How extrasolar is actually used
Predominantly used in astronomy and popular science writing. In modern usage, "exoplanet" has largely replaced "extrasolar planet" as the preferred shorthand among astronomers, though "extrasolar" remains common as an adjective in broader contexts.
Easily confused with extrasolar
"Extrasolar" means outside our solar system entirely, while "interstellar" refers to the space between stars within the galaxy.
"Extraterrestrial" means originating from anywhere beyond Earth (including within our own solar system), whereas "extrasolar" specifically means beyond our entire solar system.