The Discovery of Exoplanets
The discovery of exoplanets—planets orbiting stars beyond our solar system—has transformed our understanding of planetary systems. As of today, over 5,000 exoplanets have been confirmed, with discoveries accelerating since the launch of missions like Kepler and TESS.
Detection Methods
Transit Photometry
This technique measures the dip in a star’s brightness as a planet passes in front of it (a transit). By studying these dips, astronomers can infer the planet’s size and orbit.
Radial Velocity (Doppler Spectroscopy)
This method detects the small shifts in a star’s light caused by the gravitational pull of an orbiting planet. These shifts allow astronomers to estimate the planet's mass and orbital period.
Direct Imaging and Microlensing
Though challenging, direct imaging involves capturing actual images of exoplanets, while microlensing relies on gravitational lensing effects to detect distant planets.
Habitability
The habitable zone is the range of distances from a star where conditions might allow liquid water to exist on a planet’s surface. The discovery of potentially habitable exoplanets, such as Proxima Centauri b and those in the TRAPPIST-1 system, has sparked intense interest in the search for life beyond Earth.