page_title: Gliese 581e
hierarchical_section_title: Gliese 581e
caption_attribution_description: English: Comparison of several possible sizes for the exoplanet Gliese 581 e with the Solar System planet Earth, using approximate models of planetary radius as a function of mass[1] for several possible compositions, based on mass reported in the Open Exoplanet Catalogue[2] as of 2010-09-30. Models include: &#160;&#160; water world with a rocky core, composed of 75% H2O, 3% Fe, 22% MgSiO3 &#160;&#160; hypothetical pure water (ice) planet, the largest size for Gliese 581 e without a significant H/He envelope &#160;&#160; rocky terrestrial "Earth-like" planet, composed of 67% Fe, 32.5% MgSiO3 &#160;&#160; hypothetical pure iron planet, Gliese 581 e's theoretical smallest size Gliese 581 e is not likely to be smaller than the iron planet, and will be considerably larger than the water planet if significant H or He is present. For non-transiting planets, all modeled sizes will be underestimates to the extent that the planet's actual mass is larger than the reported minimum mass. ↑ Seager, S.; M. Kuchner, C. A. Hier-Majumder and B. Militzer (2007). "Mass–radius relationships for solid exoplanets". The Astrophysical Journal 669: 1279–1297. DOI:10.1086/521346. Retrieved on 2010-08-27. ↑ Open Exoplanet Catalogue (2010-09-30). Retrieved on 2010-09-30.
context_page_description: Gliese 581e or Gl 581e is an extrasolar planet orbiting within the Gliese 581 system, located approximately 20.4 light-years away from Earth in the Libra constellation. It is the third planet discovered in the system and the first in order from the star.
  The planet was discovered by an Observatory of Geneva team led by Michel Mayor, using the HARPS instrument on the European Southern Observatory 3.6 m telescope in La Silla, Chile. The discovery was announced on 21 April 2009. Mayor's team employed the radial velocity technique, in which the orbit size and mass of a planet are determined based on the small perturbations it induces in its parent star's orbit via gravity.
  At a minimum mass of 1.7 Earth masses, it is one of the least massive extrasolar planets discovered around a normal star, and relatively close in mass to Earth. It is also the exoplanet with the smallest accurate true mass known. At an orbital distance of just 0.03 AU from its parent star, however, it orbits further in than the habitable zone. It is unlikely to possess an atmosphere due to its high temperature and strong radiation from the star.
context_section_description: Gliese 581e /ˈɡliːzə/ or Gl 581e is an extrasolar planet orbiting within the Gliese 581 system, located approximately 20.4 light-years away from Earth in the Libra constellation. It is the third planet discovered in the system (fourth if the disputed planet candidate Gliese 581d is included) and the first in order from the star.
  The planet was discovered by an Observatory of Geneva team led by Michel Mayor, using the HARPS instrument on the European Southern Observatory 3.6 m (140 in) telescope in La Silla, Chile. The discovery was announced on 21 April 2009. Mayor's team employed the radial velocity technique, in which the orbit size and mass of a planet are determined based on the small perturbations it induces in its parent star's orbit via gravity.
  At a minimum mass of 1.7 Earth masses, it is one of the least massive extrasolar planets discovered around a normal star, and relatively close in mass to Earth. It is also the exoplanet with the smallest accurate true mass known. At an orbital distance of just 0.03 AU (4,500,000 km) from its parent star, however, it orbits further in than the habitable zone. It is unlikely to possess an atmosphere due to its high temperature and strong radiation from the star. Although scientists think it probably has a rocky surface similar to Earth, it is also likely to experience intense tidal heating similar to (and likely more intense than) that affecting Jupiter's moon Io. Gliese 581e completes an orbit around its parent star in approximately 3.15 days.
caption: Size comparison of Gliese 581e with Earth.
  (Based on selected hypothetical modeled compositions)
exif: {}