Butler, R. Paul Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington DC.
Traub, Wesley A. Exoplanet Exploration Program, Jet Propulsion Laboratory, National Aeronautics and Space Administration; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California.
Last reviewed:July 2018
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- Detection techniques
- Direct imaging
- Indirect detection
- Exoplanet properties
- Planetary orbits
- Planetary masses and radii
- Planetary atmospheres
- Habitable zone
- The planetary zoo
- Solar system analogs
- Hot Jupiters
- Links to Primary Literature
- Additional Readings
Planets beyond our solar system. For millennia, humankind has known about most of the major planets in our solar system because these worlds are visible to the naked eye. Exoplanets, however, were not indisputably known until 1995, when astronomers discovered the first planet orbiting a typical star like the Sun. Since then, and using a variety of detection techniques, scientists have uncovered thousands of exoplanets. The current tally, as of July 2018, stands at 3,774 confirmed exoplanets, with another 5,000 awaiting confirmation through corroborative measurements by additional instruments. Because almost all stars seem to form and host planets, this running tally is but a small fraction of the hundreds of billions of exoplanets expected to exist just in the Milky Way Galaxy alone (Fig. 1). See also: Planet; Solar system; Star
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