Key Terms & Concepts — UPSC Mains
Exoplanet
"A planet that orbits a star outside our solar system, key to the search for habitable worlds and life beyond Earth"
An exoplanet, or extrasolar planet, is a planet that orbits a star other than the Sun. Most are detected indirectly, through the tiny dip in a star's brightness when a planet transits across it (the transit method) or through the star's slight wobble caused by the planet's gravity (the radial-velocity method). Studying exoplanets, especially those in the habitable zone where liquid water could exist, is central to understanding planet formation and the possibility of life elsewhere. In 2026 the confirmed tally of exoplanets crossed 6,000.
Relevant for GS3 (space science, astronomy, frontier research). Exoplanet science drives missions and instruments such as the James Webb Space Telescope and links to India's own astronomy efforts. The 6,000-exoplanet milestone in 2026 and Webb's atmospheric studies of distant worlds make it a topical Prelims fact and a Mains angle on scientific frontiers.
- 1 An exoplanet orbits a star outside our solar system; the first around a Sun-like star was confirmed in 1995
- 2 [object Object]
- 3 NASA's confirmed exoplanet count crossed 6,000 in 2026
- 4 The habitable or 'Goldilocks' zone is the orbital band where liquid water could persist
- 5 The James Webb Space Telescope analyses exoplanet atmospheres for gases such as methane and water
- 6 India's AstroSat and planned missions contribute to exoplanet and stellar studies
- 7 Kepler and TESS space telescopes have been the biggest sources of exoplanet discoveries
In 2026 the confirmed count of exoplanets passed 6,000, while the James Webb Space Telescope detected methane and Earth-like temperatures on the Saturn-sized world TOI-199b, deepening the search for potentially habitable planets.
