Concepts

Exoplanet

Also Known As Extrasolar Planet

Citation Formats

General Reference

Space and Astronomy Atlas. "Exoplanet." Accessed August 30, 2026. https://space.interactiveatlas.org/concepts/exoplanet.

APA Style

Space and Astronomy Atlas. (n.d.). Exoplanet. Retrieved August 30, 2026, from https://space.interactiveatlas.org/concepts/exoplanet

BibTeX

@misc{spaceandastronomyatlas-exoplanet,
  author = {Space and Astronomy Atlas},
  title = {Exoplanet},
  year = {2026},
  url = {https://space.interactiveatlas.org/concepts/exoplanet},
  note = {Accessed August 30, 2026}
}

A planet that orbits a star other than the Sun. The first confirmed around a Sun-like star, 51 Pegasi b, was announced in 1995, and space telescopes such as Kepler have since raised the confirmed count into the thousands, spanning types from scorching gas giants to rocky worlds.

Facts

Concept Domain

Planetary Science 1

Formulated Year

1995 2

Year of the announcement of 51 Pegasi b, the first confirmed planet around a Sun-like star; planets orbiting a pulsar had been reported in 1992.

Proposed By

The scientific search for exoplanets was formally proposed by astronomer Otto Struve in 1952, who argued planets could orbit much closer to their stars than in the Solar System and proposed Doppler spectroscopy and the transit method as detection techniques. 1

Cross-Tradition Connections

Associated With

Drake Equation

Source Wikipedia (space and spaceflight articles)

Drake Equation

Source Wikipedia (space and spaceflight articles)

Habitable Zone

The habitable zone concept is a central tool for assessing exoplanet habitability.

Source Wikipedia (space and spaceflight articles)

Habitable Zone

Source Wikipedia (space and spaceflight articles)

Kepler Space Telescope

Kepler confirmed thousands of exoplanets by the transit method.

Source NASA Solar System Exploration

Sources

1. Wikipedia (space and spaceflight articles)

Wikimedia FoundationExoplanet, History of detection, Early speculations section

Quote, Exoplanet, History of detection, Early speculations section

In 1952, more than 40 years before the first hot Jupiter was discovered, Otto Struve wrote that there is no compelling reason that planets could not be much closer to their parent star than is the case in the Solar System, and proposed that Doppler spectroscopy and the transit method could detect super-Jupiters in short orbits.

1. Wikipedia (space and spaceflight articles)

Wikimedia FoundationAssociated With: Habitable Zone

1. Wikipedia (space and spaceflight articles)

Wikimedia FoundationAssociated With: Drake Equation

1. Wikipedia (space and spaceflight articles)

Wikimedia FoundationAssociated With: Habitable Zone

1. Wikipedia (space and spaceflight articles)

Wikimedia FoundationAssociated With: Drake Equation

2. Encyclopedia Britannica: Space Exploration

Encyclopedia Britannica, Inc.

NASA Solar System Exploration

National Aeronautics and Space AdministrationAssociated With: Kepler Space Telescope