An exoplanet is a planet orbiting a star other than the Sun. Of particular interest are planets that may orbit in their star’s habitable zone, the distance from a star where temperatures allow liquid water to persist on a planet’s surface, given a suitable atmosphere. Since water is necessary for life as we know it, its presence is required for worlds to be considered capable of supporting life. Exoplanets can also teach us more about planets in the universe, such as the diversity of planets in the galaxy, how they interact with their host stars and with each other, and how common solar systems like ours really are.
Using a wide variety of methods, astronomers have discovered more than 3,700 exoplanets to date, largely thanks to NASA's Kepler/K2 mission
Other NASA missions also play a key role in detecting exoplanets. The Transiting Exoplanet Survey Satellite
, which launched in April 2018, will monitor 200,000 of the brightest dwarf stars for transiting exoplanets. Future missions like the James Webb Space Telescope
will be able to study these discovered planets in greater detail, helping determine their composition.
Researchers in NASA Goddard Space Flight Center's Sellers Exoplanet Environments Collaboration
are leveraging work across disciplines to better understand exoplanets. Areas like planet-star interactions, planetary formation, and even study of the Earth itself enable researchers to develop tools to learn more about how exoplanets evolve, and what ingredients are necessary to support life.