Transit photometry

Number of extrasolar planet discoveries per year through 2022, with colors indicating method of detection: Direct imaging Microlensing Transit Radial velocity TimingMethods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the glare from the parent star washes it out. For those reasons, very few of the exoplanets reported as of June 2025 have been detected directly, with even fewer being resolved from their host star. Established detection methodseditThe following methods have proven successful at least once for discovering a new planet or detecting an already discovered planet: Radial velocityeditRadial velocity graph of 18 Delphini b.A star with a planet will move in its own small orbit in response to the planet's gravity. This leads to variations in the speed with which the star moves toward or a