# Gliese 581e

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Terrestrial planet orbiting Gliese 581

Gliese 581e Size comparison of Gliese 581e with Earth (Based on selected hypothetical modeled compositions)[a] Discovery[1] Discovered by Mayor et al. Discovery site La Silla Observatory, Chile Discovery date 21 April 2009 Detection method Radial velocity Orbital characteristics[2] Semi-major axis 0.02799±0.0003 AU Eccentricity 0.012+0.015 −0.008 Orbital period (sidereal) 3.1481±0.0004 d Inclination 47°+15° −13° Time of periastron 2454752.33 ± 0.05[3] Argument of periastron 226°+91° −55° Semi-amplitude 1.8±0.1 m/s Star Gliese 581 Physical characteristics[2] Mass 2.48+0.70 −0.42 M🜨

**Gliese 581e** [/ˈɡliːzə/](https://en.wikipedia.org/wiki/Help:IPA/English) or **Gl 581e** is an [exoplanet](/source/Exoplanet) orbiting within the [Gliese 581](/source/Gliese_581) system, located 20.5 [light-years](/source/Light-year) (6.3 [parsecs](/source/Parsec)) away from [Earth](/source/Earth) in the [Libra constellation](/source/Libra_constellation). It is the third planet discovered in the system (fourth if the disputed planet candidate [Gliese 581d](/source/Gliese_581d) is included) and the first in order from the star.

## Discovery

The planet was [discovered](/source/Discovery_(observation)) by an [Observatory of Geneva](/source/Observatory_of_Geneva) team led by [Michel Mayor](/source/Michel_Mayor), using the [HARPS](/source/High_Accuracy_Radial_Velocity_Planet_Searcher) instrument on the [European Southern Observatory](/source/European_Southern_Observatory) 3.6 m (140 in) [telescope](/source/Telescope) in [La Silla](/source/La_Silla_Observatory), [Chile](/source/Chile). The discovery was announced on 21 April 2009. Mayor's team employed the [radial velocity](/source/Radial_velocity) technique, in which the orbit size and [mass](/source/Mass) of a [planet](/source/Planet) are determined based on the small perturbations it induces in its parent star's [orbit](/source/Orbit) via [gravity](/source/Gravitation).[1]

## Characteristics

With a [minimum mass](/source/Minimum_mass) of about 1.9 [Earth masses](/source/Earth_mass), Gliese 581e was the least massive exoplanet known around a normal star at the time of discovery in 2009, with only [PSR B1257+12 A](/source/PSR_B1257%2B12_A) being less massive.[4][5] A 2024 study determined the [orbital inclination](/source/Orbital_inclination) of the planet, allowing its true mass to be determined, which is about 30% greater than the minimum mass at about 2.5 Earth masses.[2]

Gliese 581e completes an orbit around its parent star in 3.15 days. At an orbital distance of just 0.028 [AU](/source/Astronomical_unit) (4,200,000 km) from its parent star, it orbits further in than the [habitable zone](/source/Habitable_zone).[3] 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](/source/Io_(moon)).[6]

## See also

- [Habitability of red dwarf systems](/source/Habitability_of_red_dwarf_systems)

## Notes

1. **[^](#cite_ref-1)** The estimated range of sizes in this image from 2009 is based on the planet's [minimum mass](/source/Minimum_mass). Since the true mass is now known to be somewhat greater, the sizes may be underestimated.

## References

1. ^ [***a***](#cite_ref-mayor_2-0) [***b***](#cite_ref-mayor_2-1) Mayor, Michel; Bonfils, Xavier; Forveille, Thierry; et al. (2009). ["The HARPS search for southern extra-solar planets, XVIII. An Earth-mass planet in the GJ 581 planetary system"](https://web.archive.org/web/20090521052641/http://obswww.unige.ch/~udry/Gl581_preprint.pdf) (PDF). *[Astronomy and Astrophysics](/source/Astronomy_and_Astrophysics)*. **507** (1): 487–494. [arXiv](/source/ArXiv_(identifier)):[0906.2780](https://arxiv.org/abs/0906.2780). [Bibcode](/source/Bibcode_(identifier)):[2009A&A...507..487M](https://ui.adsabs.harvard.edu/abs/2009A&A...507..487M). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/200912172](https://doi.org/10.1051%2F0004-6361%2F200912172). [S2CID](/source/S2CID_(identifier)) [2983930](https://api.semanticscholar.org/CorpusID:2983930). Archived from [the original](http://obswww.unige.ch/~udry/Gl581_preprint.pdf) (PDF) on 21 May 2009.

1. ^ [***a***](#cite_ref-vonStauffenberg2024_3-0) [***b***](#cite_ref-vonStauffenberg2024_3-1) [***c***](#cite_ref-vonStauffenberg2024_3-2) von Stauffenberg, A.; Trifonov, T.; Quirrenbach, A.; et al. (2024-06-05). "The CARMENES search for exoplanets around M dwarfs. Revisiting the GJ 581 multi-planetary system with new Doppler measurements from CARMENES, HARPS, and HIRES". *Astronomy & Astrophysics*. [arXiv](/source/ArXiv_(identifier)):[2407.11520](https://arxiv.org/abs/2407.11520). [Bibcode](/source/Bibcode_(identifier)):[2024A&A...688A.112V](https://ui.adsabs.harvard.edu/abs/2024A&A...688A.112V). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202449375](https://doi.org/10.1051%2F0004-6361%2F202449375). [ISSN](/source/ISSN_(identifier)) [0004-6361](https://search.worldcat.org/issn/0004-6361).

1. ^ [***a***](#cite_ref-robertson2014_4-0) [***b***](#cite_ref-robertson2014_4-1) Robertson, Paul; [Mahadevan, Suvrath](/source/Suvrath_Mahadevan); Endl, Michael; Roy, Arpita (3 July 2014). "Stellar activity masquerading as planets in the habitable zone of the M dwarf Gliese 581". *[Science](/source/Science_(journal))*. **345** (6195): 440–444. [arXiv](/source/ArXiv_(identifier)):[1407.1049](https://arxiv.org/abs/1407.1049). [Bibcode](/source/Bibcode_(identifier)):[2014Sci...345..440R](https://ui.adsabs.harvard.edu/abs/2014Sci...345..440R). [doi](/source/Doi_(identifier)):[10.1126/science.1253253](https://doi.org/10.1126%2Fscience.1253253). [PMID](/source/PMID_(identifier)) [24993348](https://pubmed.ncbi.nlm.nih.gov/24993348). [S2CID](/source/S2CID_(identifier)) [206556796](https://api.semanticscholar.org/CorpusID:206556796).

1. **[^](#cite_ref-5)** Rincon, Paul; Amos, Jonathan (2009-04-21). ["Lightest exoplanet is discovered"](http://news.bbc.co.uk/1/hi/sci/tech/8008683.stm). [BBC](/source/BBC). [Archived](https://web.archive.org/web/20090424061149/http://news.bbc.co.uk/1/hi/sci/tech/8008683.stm) from the original on 2009-04-24. Retrieved 2009-04-21.

1. **[^](#cite_ref-6)** Overbye, Dennis (April 21, 2009). ["Astronomers Find Planet Closer to Size of Earth"](https://www.nytimes.com/2009/04/22/science/22planet.html). *[New York Times](/source/New_York_Times)*. [Archived](https://web.archive.org/web/20170312213033/http://www.nytimes.com/2009/04/22/science/22planet.html) from the original on March 12, 2017. Retrieved February 24, 2017.

1. **[^](#cite_ref-7)** Barnes, Rory; Jackson, Brian; Greenberg, Richard; Raymond, Sean N. (2009-06-09). "Tidal Limits to Planetary Habitability". *The Astrophysical Journal*. **700** (1): L30–L33. [arXiv](/source/ArXiv_(identifier)):[0906.1785](https://arxiv.org/abs/0906.1785). [Bibcode](/source/Bibcode_(identifier)):[2009ApJ...700L..30B](https://ui.adsabs.harvard.edu/abs/2009ApJ...700L..30B). [doi](/source/Doi_(identifier)):[10.1088/0004-637X/700/1/L30](https://doi.org/10.1088%2F0004-637X%2F700%2F1%2FL30). [S2CID](/source/S2CID_(identifier)) [16695095](https://api.semanticscholar.org/CorpusID:16695095).

## External links

Media related to [Gliese 581 e](https://commons.wikimedia.org/wiki/Category:Gliese_581_e) at Wikimedia Commons [Discovery of smallest exoplanet yields 'extraordinary' find](https://en.wikinews.org/wiki/Discovery_of_smallest_exoplanet_yields_%27extraordinary%27_find) at [Wikinews](/source/Wikinews)

- [Lightest exoplanet yet discovered](https://web.archive.org/web/20090705084859/http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html) [European Southern Observatory](/source/European_Southern_Observatory) press release

- [Scientists discover a nearly Earth-sized planet](https://news.yahoo.com/s/ap/20090421/ap_on_sc/eu_britain_new_planet) [Archived](https://web.archive.org/web/20090429221450/http://news.yahoo.com/s/ap/20090421/ap_on_sc/eu_britain_new_planet) 2009-04-29 at the [Wayback Machine](/source/Wayback_Machine)

- [Publications at Exoplanet.eu](http://exoplanet.eu/planet.php?p1=Gl+581&p2=e&showPubli=yes&sortByDate#a_publi) [Archived](https://web.archive.org/web/20110602113129/http://exoplanet.eu/planet.php?p1=Gl+581&p2=e&showPubli=yes&sortByDate#a_publi) 2011-06-02 at the [Wayback Machine](/source/Wayback_Machine)

v t e Gliese 581 system Star Gliese 581 Planets Gliese 581e Gliese 581b Gliese 581c Gliese 581g† Gliese 581d? Gliese 581f† Messages A Message from Earth Hello from Earth † - Disproven Category:Gliese 581 Portal:Astronomy

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Adapted from the Wikipedia article [Gliese 581e](https://en.wikipedia.org/wiki/Gliese_581e) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Gliese_581e?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.