NASA Hits 6,128 Confirmed Exoplanets
NASA's Exoplanet Archive hit 6,128 confirmed worlds, up from the first discoveries like 51 Pegasi b in the 1990s. Kepler and TESS transits revealed super-Earths, puffy Neptunes, and habitable zone candidates — the upcoming Roman Telescope will use microlensing to find more.
The first confirmed exoplanet detection wasn't around a Sun-like star, but a pulsar. In 1992, astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two rocky planets orbiting the pulsar PSR B1257+12, deduced from irregularities in the star's radio wave pulses. A third planet was confirmed in the same system in 1994. The transit method, which observes the dimming of a star as a planet passes in front of it, has been the most prolific exoplanet detection technique to date. This method not only confirms a planet's existence but can also help determine its size. NASA's Kepler Space Telescope, a pioneer of this method, is credited with the discovery of over 2,600 confirmed worlds. While the transit method has been highly successful, the radial velocity method has also been a key player in exoplanet discovery. This technique detects the "wobble" of a star caused by the gravitational pull of an orbiting planet, observed as a shift in the star's light spectrum. The first exoplanet found orbiting a main-sequence star, 51 Pegasi b, was discovered in 1995 using this method by Michel Mayor and Didier Queloz. The upcoming Nancy Grace Roman Space Telescope, slated to launch by May 2027, will employ gravitational microlensing to uncover new worlds. This technique observes the bending and magnifying of light from a distant star by the gravity of a closer star and its planets, an effect first proposed by Einstein in the 1930s. This method is particularly effective at finding planets further from their host stars. With a field of view 100 to 200 times greater than Hubble's, the Roman Telescope is expected to discover thousands of new exoplanets during its five-year prime mission. Its survey of the inner Milky Way will be sensitive enough to find planets with masses as small as one-tenth of Earth's. Beyond just counting planets, Roman will also directly image some of these distant worlds using a coronagraph. This instrument blocks the host star's bright light, allowing for the direct detection of exoplanets and analysis of their atmospheric composition, a significant step in the search for habitable worlds.
