exoplanetám

Exoplanets, or extrasolar planets, are planets that orbit stars other than the Sun. Since the first confirmed detections in the 1990s, thousands have been found, spanning a wide range of sizes, compositions, and orbital configurations. Detection methods include the transit method, where a planet passes in front of its star causing a dip in brightness, and the radial velocity method, which measures star wobbles due to gravitational pull. Other methods include direct imaging, gravitational microlensing, and astrometry.

Many exoplanets are gas giants larger than Neptune, including hot Jupiters that orbit very close to their stars. There are also smaller rocky planets, including super-Earths and Earth-sized planets, some within the habitable zone where liquid water could exist. The diversity of exoplanets has challenged ideas about planet formation and evolution and revealed planetary systems with architectures unlike our own.

Key missions such as NASA's Kepler and its successor K2, and the Transiting Exoplanet Survey Satellite (TESS), have driven the discovery count. Ground-based surveys using high-precision spectrographs, like HARPS, have contributed by measuring stellar radial-velocity signals. The study of exoplanets is interdisciplinary, involving astronomy, astrophysics, planetary science, and astrobiology.

Notable examples include the TRAPPIST-1 system with seven roughly Earth-sized planets; Proxima Centauri b, orbiting the Sun's nearest star; and many multi-planet systems. Future facilities, including James Webb Space Telescope and upcoming ground-based extremely large telescopes, aim to characterize atmospheres and search for biosignatures, advancing the search for potentially habitable worlds.