Gliese 876 e is an exoplanet orbiting the star

Gliese 876 Gliese 876 is a red dwarf approximately 15 light-years away from Earth in the constellation of Aquarius. It is one of the closest known stars to the Sun confirmed to possess a planetary system with more than two planets, after Gliese 1061 ...

in the constellation of

Aquarius Aquarius may refer to: Astrology * Aquarius (astrology), an astrological sign * Age of Aquarius, a time period in the cycle of astrological ages Astronomy * Aquarius (constellation) * Aquarius in Chinese astronomy Arts and entertainme ...

. It is in a 1:2:4 Laplace resonance with the planets

Gliese 876 c Gliese 876 c is an exoplanet orbiting the red dwarf Gliese 876, taking about 30 days to complete an orbit. The planet was discovered in April 2001 and is the second planet in order of increasing distance from its star. Discovery At the time of ...

and

Gliese 876 b Gliese 876 b is an exoplanet orbiting the red dwarf Gliese 876. It completes one orbit in approximately 61 days. Discovered in June 1998, Gliese 876 b was the first planet to be discovered orbiting a red dwarf. Discovery Gliese 876 b was initiall ...

: for each orbit of planet e, planet b completes two orbits and planet c completes four. This configuration is the second known example of a Laplace resonance after

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

's moons Io,

Europa Europa may refer to: Places * Europe * Europa (Roman province), a province within the Diocese of Thrace * Europa (Seville Metro), Seville, Spain; a station on the Seville Metro * Europa City, Paris, France; a planned development * Europa Cliff ...

and Ganymede. Its orbit takes 124 days to complete. Gliese 876 e has a mass similar to that of the planet

Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus ( Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of ...

. Its orbit takes 124 days to complete, or roughly one third of a year. While the orbital period is longer than that of Mercury around the Sun, the lower mass of the host star relative to the Sun means the planet's orbit has a slightly smaller

semimajor axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the lo ...

. Unlike Mercury, Gliese 876 e has a nearly circular orbit with an eccentricity of 0.055 ± 0.012. This planet, like b and c, has likely migrated inward.

References

Gliese 876 Aquarius (constellation) Exoplanets discovered in 2010 Exoplanets detected by radial velocity Giant planets 8 {{extrasolar-planet-stub