Gliese 581g: Difference between revisions

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	== Habitability ==		== Habitability ==
	] planetary system. In the picture, Gliese 581 g is plotted with a circular orbit between c and d. The eccentricity of d is currently unknown; previously unknown planets such as g may have inflated its first-reported value.]]		] planetary system. In the picture, Gliese 581 g is plotted with a circular orbit between c and d. The eccentricity of d is currently unknown; previously unknown planets such as g may have inflated its first-reported value.]]
		⚫	Despite there being other planets between Gliese 581 g and the parent star that are not tidally locked, due to the planet's size it is at the right distance to be ] to Gliese 581, just as our moon always presents the same face to the Earth; the length of Gliese 581 g's ] would then precisely match the length of its year.<ref name = "Vogt"/><ref> {{Cite web\|url=http://news.sciencemag.org/sciencenow/2010/09/astronomers-find-most-earth-like.html\|title=Astronomers Find Most Earth-like Planet to Date\|publisher=], USA\|date=September 29, 2010\|accessdate=September 30, 2010}}</ref> Tidal locking would mean the planet would have no ] and therefore no ] in any normal sense of the word. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, likely one that is denser than Earth's.<ref name = "Vogt"/> Researchers have estimated that the surface temperature of the planet averages between −31 to −12 degrees Celsius (−24 and 10 degrees Fahrenheit).<ref name="Stephens">{{cite web \|last=Stephens \|first=Tim \|date=2010-09-29 \|url=http://news.ucsc.edu/2010/09/planet.html \|title=Newly discovered planet may be first truly habitable exoplanet \|work=University News & Events \|publisher=]}}</ref> With one side of the planet always facing the star, temperatures would range from blazing hot in the light side to freezing cold in the dark side, with continuous Earth-like temperatures imaginable along the ] (the area between the bright and the dark side), informally known as the ].
⚫	In an interview with Lisa-Joy Zgorski of the ], Steven Vogt was asked what he thought about the chances of life existing on Gliese 581 g. . Event occurs at 41:25-42:31. See {{cite news \|last=Overbye \|first=Dennis \|authorlink=Dennis Overbye \|date=2010-09-29 \|url=http://www.nytimes.com/2010/09/30/science/space/30planet.html?_r=1 \|title=New Planet May Be Able to Nurture Organisms \|publisher='']''\|accessdate=September 30, 2010}}</ref>

	For comparison, ] vary from lows of about -87 ] during the polar winters to highs of up to -5 °C in summers.<ref>{{cite web \| url=http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars&Display=Facts \| title=NASA, Mars: Facts & Figures \| accessdate=2010-01-28 }}</ref> The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low ] of Martian soil.<ref>{{cite web \| title=Mars' desert surface... \| work=MGCM Press release \| publisher=NASA \| url=http://www-mgcm.arc.nasa.gov/mgcm/HTML/WEATHER/surface.html \| accessdate=2007-02-25 }}</ref> A low atmosphere is similar to a tidally locked atmosphere in that way.		For comparison, ] vary from lows of about -87 ] during the polar winters to highs of up to -5 °C in summers.<ref>{{cite web \| url=http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars&Display=Facts \| title=NASA, Mars: Facts & Figures \| accessdate=2010-01-28 }}</ref> The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low ] of Martian soil.<ref>{{cite web \| title=Mars' desert surface... \| work=MGCM Press release \| publisher=NASA \| url=http://www-mgcm.arc.nasa.gov/mgcm/HTML/WEATHER/surface.html \| accessdate=2007-02-25 }}</ref> A low atmosphere is similar to a tidally locked atmosphere in that way.

⚫	~~Because~~ of Gliese 581 g's ~~proximity~~ ~~to its~~ parent star, it is ~~predicted~~ to be ] to Gliese 581. ~~Just~~ as our moon always presents the same face to the Earth, the length of Gliese 581 g's ] would then precisely match the length of its year.<ref name = "Vogt"/><ref> {{Cite web\|url=http://news.sciencemag.org/sciencenow/2010/09/astronomers-find-most-earth-like.html\|title=Astronomers Find Most Earth-like Planet to Date\|publisher=], USA\|date=September 29, 2010\|accessdate=September 30, 2010}}</ref> Tidal locking would mean the planet would have no ] and therefore no ] in any normal sense of the word. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, likely one that is denser than Earth's.<ref name = "Vogt"/> Researchers have estimated that the ~~global average~~ surface temperature of the planet averages between −31 to −12 degrees Celsius (−24 and 10 degrees Fahrenheit).<ref name="Stephens">{{cite web \|last=Stephens \|first=Tim \|date=2010-09-29 \|url=http://news.ucsc.edu/2010/09/planet.html \|title=Newly discovered planet may be first truly habitable exoplanet \|work=University News & Events \|publisher=]}}</ref> With one side of the planet always facing the star, temperatures would range from blazing hot in the light side to freezing cold in the dark side, with continuous Earth-like temperatures imaginable along the ] (the area between the bright and the dark side), informally known as the ].

	Theoretical models predict that volatile ]s such as ] and ], if present, might evaporate in the scorching heat of the sunward side, migrate to the cooler night side, and condense to form ]s. Over time, the entire atmosphere might freeze into ice caps on the night side of the planet. Alternatively, an atmosphere large enough to be stable would circulate the heat more evenly, allowing for a wider habitable area on the surface.<ref>{{cite web \|url=http://www.sciam.com/article.cfm?chanID=sa004&articleID=000CC344-B043-1353-AF3383414B7FFE9F \| title=Red Star Rising \| last=Alpert \| first=Mark \| date=2005-11-07 \| publisher=Scientific American \| accessdate = 2007–04–25}}</ref> For example, although ] has a small axial inclination, very little sunlight reaches the surface at the poles. A slow rotation rate approximately 117 times slower than Earth's produces prolonged days and nights. Despite the uneven distribution of sunlight cast on Venus at any given time, polar areas and the night side of Venus are kept almost as hot as on the day side by globally circulating winds.<ref>{{cite web\|title = Titan, Mars and Earth: Entropy Production by Latitudinal Heat Transport\|author=Ralph D Lorenz, Jonathan I Lunine, Paul G Withers, Christopher P. McKay\|work=], University of Arizona Lunar and Planetary Laboratory\|url=http://sirius.bu.edu/withers/pppp/pdf/mepgrl2001.pdf\|format=PDF\|year=2001\|accessdate=2007-08-21}}</ref> However, it remains unknown if water and/or carbon dioxide are even present on the surface of Gliese 581 g.		Theoretical models predict that volatile ]s such as ] and ], if present, might evaporate in the scorching heat of the sunward side, migrate to the cooler night side, and condense to form ]s. Over time, the entire atmosphere might freeze into ice caps on the night side of the planet. Alternatively, an atmosphere large enough to be stable would circulate the heat more evenly, allowing for a wider habitable area on the surface.<ref>{{cite web \|url=http://www.sciam.com/article.cfm?chanID=sa004&articleID=000CC344-B043-1353-AF3383414B7FFE9F \| title=Red Star Rising \| last=Alpert \| first=Mark \| date=2005-11-07 \| publisher=Scientific American \| accessdate = 2007–04–25}}</ref> For example, although ] has a small axial inclination, very little sunlight reaches the surface at the poles. A slow rotation rate approximately 117 times slower than Earth's produces prolonged days and nights. Despite the uneven distribution of sunlight cast on Venus at any given time, polar areas and the night side of Venus are kept almost as hot as on the day side by globally circulating winds.<ref>{{cite web\|title = Titan, Mars and Earth: Entropy Production by Latitudinal Heat Transport\|author=Ralph D Lorenz, Jonathan I Lunine, Paul G Withers, Christopher P. McKay\|work=], University of Arizona Lunar and Planetary Laboratory\|url=http://sirius.bu.edu/withers/pppp/pdf/mepgrl2001.pdf\|format=PDF\|year=2001\|accessdate=2007-08-21}}</ref> However, it remains unknown if water and/or carbon dioxide are even present on the surface of Gliese 581 g.
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	\| accessdate = 2010-09-29		\| accessdate = 2010-09-29
	}}</ref>		}}</ref>

		⚫	In an interview with Lisa-Joy Zgorski of the ], Steven Vogt was asked what he thought about the chances of life existing on Gliese 581 g. Vogt was optimistic: "I'm not a biologist, nor do I want to play one on TV. Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that, my own personal feeling is that the chances of life on this planet are 100%. I have almost no doubt about it."<ref>NSF. . Event occurs at 41:25-42:31. See {{cite news \|last=Overbye \|first=Dennis \|authorlink=Dennis Overbye \|date=2010-09-29 \|url=http://www.nytimes.com/2010/09/30/science/space/30planet.html?_r=1 \|title=New Planet May Be Able to Nurture Organisms \|publisher='']'\|accessdate=September 30, 2010}}</ref>

	== See also ==		== See also ==

Revision as of 21:02, 30 September 2010

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Template:Planetbox begin Template:Planetbox image Template:Planetbox star Template:Planetbox orbit Template:Planetbox character Template:Planetbox discovery Template:Planetbox reference Template:Planetbox end

Gliese 581 g (Template:Pron-en) or Gl 581 g is one of at least six extrasolar planets found around the M3V red dwarf star Gliese 581, approximately 20.5 light-years away from Earth in the constellation of Libra. It is the sixth planet discovered in the Gliese 581 planetary system and the fourth in order from the star.

Discovered by the Lick-Carnegie Exoplanet Survey after more than a decade's worth of observations, results imply that the planet is located in the middle of the "Goldilocks", or habitable zone of its parent star, where the existence of liquid water is considered a strong possibility. The discovery of Gliese 581 g was announced in late September 2010, and is believed to be the first Goldilocks planet ever found, the most Earth-like planet, and the best exoplanet candidate with the potential for harboring life found to date.

Discovery

The planet was detected by a team of astronomers in the Lick-Carnegie Exoplanet Survey, led by principal investigator Steven Vogt, professor of astronomy and astrophysics at the University of California, Santa Cruz and co-investigator Paul Butler of the Carnegie Institution of Washington. The discovery was made using radial velocity measurements combining 11 years of data from the HIRES instrument of the Keck 1 telescope and the HARPS instrument of ESO's 3.6m telescope at La Silla Observatory.

The planet is believed to have a mass of 3.1 to 4.3 times that of the Earth and a radius of 1.3 to 2 times that of Earth. Is has an orbital period of just under 37 days, orbiting at a distance of 0.146 AU from its parent star.

The discovery of a habitable planet so early in the search for exoplanets, after scientists had monitored only a relatively small number of stars for this purpose, could mean that such planets are more widely distributed than had been believed. Vogt now believes that the ratio of systems with habitable planets is 10%—20%.

The Steven Vogt et al. team has unofficially adopted the name "Zarmina's World" for the planet, after Vogt's wife. At the moment, according to the IAU, there is no agreed system for designating planets orbiting around other stars, nor is there any plan to create a naming system for extra-solar planets . A trend that is gaining most prominence uses a lower-case letter (starting with "b") to extend the star's designation, so "Gliese 581 g" will likely remain the official name.

Habitability

The orbits of the Gliese 581 planetary system. In the picture, Gliese 581 g is plotted with a circular orbit between c and d. The eccentricity of d is currently unknown; previously unknown planets such as g may have inflated its first-reported value.

Despite there being other planets between Gliese 581 g and the parent star that are not tidally locked, due to the planet's size it is at the right distance to be tidally locked to Gliese 581, just as our moon always presents the same face to the Earth; the length of Gliese 581 g's sidereal day would then precisely match the length of its year. Tidal locking would mean the planet would have no axial tilt and therefore no seasonality in any normal sense of the word. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, likely one that is denser than Earth's. Researchers have estimated that the surface temperature of the planet averages between −31 to −12 degrees Celsius (−24 and 10 degrees Fahrenheit). With one side of the planet always facing the star, temperatures would range from blazing hot in the light side to freezing cold in the dark side, with continuous Earth-like temperatures imaginable along the terminator (the area between the bright and the dark side), informally known as the twilight zone.

For comparison, Martian surface temperatures vary from lows of about -87 °C during the polar winters to highs of up to -5 °C in summers. The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil. A low atmosphere is similar to a tidally locked atmosphere in that way.

Theoretical models predict that volatile compounds such as water and carbon dioxide, if present, might evaporate in the scorching heat of the sunward side, migrate to the cooler night side, and condense to form ice caps. Over time, the entire atmosphere might freeze into ice caps on the night side of the planet. Alternatively, an atmosphere large enough to be stable would circulate the heat more evenly, allowing for a wider habitable area on the surface. For example, although Venus has a small axial inclination, very little sunlight reaches the surface at the poles. A slow rotation rate approximately 117 times slower than Earth's produces prolonged days and nights. Despite the uneven distribution of sunlight cast on Venus at any given time, polar areas and the night side of Venus are kept almost as hot as on the day side by globally circulating winds. However, it remains unknown if water and/or carbon dioxide are even present on the surface of Gliese 581 g.

If confirmed, the discovery of Gliese 581 g, a planet of 1.3 – 2 Earth radii orbiting in the habitable zone of such a nearby star implies an interesting lower limit on the fraction of stars that have at least one potentially habitable planet as there are only 116 known solar-type or later stars out to the 6.3 parsec distance of Gliese 581.

In an interview with Lisa-Joy Zgorski of the National Science Foundation, Steven Vogt was asked what he thought about the chances of life existing on Gliese 581 g. Vogt was optimistic: "I'm not a biologist, nor do I want to play one on TV. Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say that, my own personal feeling is that the chances of life on this planet are 100%. I have almost no doubt about it."

References

About 193 trillion kilometres
Shiga, David (2010-09-29). "Found: first rocky exoplanet that could host life". New Scientist. Retrieved September 30, 2010. {{cite news}}: Italic or bold markup not allowed in: |publisher= (help)
^ Vogt, Steven S. (2010-09-29). "The Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the Nearby M3V Star Gliese 581". accepted by the Astrophysical Journal. Retrieved 2010-09-29. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) Cite error: The named reference "Vogt" was defined multiple times with different content (see the help page).
"Just-right planet that can support life detected". Reuters, USA. September 29, 2010. Retrieved September 30, 2010.
Alleyne, Richard (September 30, 2010). "Gliese 581g the most Earth like planet yet discovered". The Daily Telegraph. Retrieved September 30, 2010. {{cite news}}: Italic or bold markup not allowed in: |publisher= (help)
Berardelli, Phil (2010-09-29). "Astronomers Find Most Earth-like Planet to Date". AAAS. Retrieved September 30, 2010.
Borenstein, Seth (2010-09-29). "Could 'Goldilocks' planet be just right for life?". Associated Press. Retrieved September 30, 2010.
"Astronomers Find Most Earth-like Planet to Date". Science, USA. September 29, 2010. Retrieved September 30, 2010.
Stephens, Tim (2010-09-29). "Newly discovered planet may be first truly habitable exoplanet". University News & Events. University of California, Santa Cruz.
"NASA, Mars: Facts & Figures". Retrieved 2010-01-28.
"Mars' desert surface..." MGCM Press release. NASA. Retrieved 2007-02-25.
Alpert, Mark (2005-11-07). "Red Star Rising". Scientific American. Retrieved 2007–04–25. {{cite web}}: Check date values in: |accessdate= (help)
Ralph D Lorenz, Jonathan I Lunine, Paul G Withers, Christopher P. McKay (2001). "Titan, Mars and Earth: Entropy Production by Latitudinal Heat Transport" (PDF). Ames Research Center, University of Arizona Lunar and Planetary Laboratory. Retrieved 2007-08-21.{{cite web}}: CS1 maint: multiple names: authors list (link)
(Turnbull & Tarter 2003)
NSF. Press Release 10-172 - Video. Event occurs at 41:25-42:31. See Overbye, Dennis (2010-09-29). "New Planet May Be Able to Nurture Organisms". The New York Times'. Retrieved September 30, 2010. {{cite news}}: Italic or bold markup not allowed in: |publisher= (help)

External links

National Science Foundation. "Steven Vogt and Paul Butler lead a team that discovered the first potentially habitable exoplanet". Video: Steven Vogt of UC Santa Cruz and UC Observatories and Paul Butler of the Carnegie Institution of Washington join NSF's Lisa-Joy Zgorski to announce the discovery of the first exoplanet that has the potential to support life.

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

Known celestial objects within 20 light-years

Primary member type

Celestial objects by systems. Secondary members are listed in small print.

0–10 ly →

Main-sequence
stars

A-type	Sirius (Alpha Canis Majoris) (8.7094±0.0054 ly) white dwarf B
G-type	Sun (0 ly) rest of Solar System Alpha Centauri α Cen (Rigil Kentaurus) (4.3441±0.0022 ly) K-type main-sequence star B (Toliman) red dwarf C (Proxima Centauri) (4.2465 ± 0.0003 ly) 2 (5?) planets: Ab?; Bc?; Cb, Cc?, Cd
M-type (red dwarfs)	Barnard's Star (5.9629±0.0004 ly) Wolf 359 (7.8558±0.0013 ly) 1? planets: b? Lalande 21185 (8.3044±0.0007 ly) 2 (3?) planets: b, d?, c Gliese 65 A (BL Ceti) (8.724±0.012 ly) red dwarf B (UV Ceti) Ross 154 (9.7063±0.0009 ly)

Brown dwarfs

L-type	Luhman 16 (6.5029±0.0011 ly) T-type brown dwarf B

Sub-brown dwarfs
and rogue planets

Y-type	WISE 0855−0714 (7.430±0.041 ly)

← 10–15 ly →

Subgiant stars

F-type	Procyon (Alpha Canis Minoris) (11.402±0.032 ly) white dwarf B

Main-sequence
stars

G-type	Tau Ceti (11.9118±0.0074 ly) 4 (8?) planets: (b), (c), (d), e, f, g, h, (i)
K-type	Epsilon Eridani (Ran) (10.4749±0.0037 ly) 1 (2?) planets: b (Ægir), c? 61 Cygni (11.4039±0.0012 ly) K-type main-sequence star B Epsilon Indi (11.8670±0.0041 ly) 2 T-type brown dwarfs: Ba, Bb planet Ab
M-type (red dwarfs)	Ross 248 (10.3057±0.0014 ly) Lacaille 9352 (10.7241±0.0007 ly) 2 (3?) planets: b, c, d? Ross 128 (11.0074±0.0011 ly) planet b EZ Aquarii (11.109±0.034 ly) 2 red dwarfs: B, C Struve 2398 (11.4908±0.0009 ly) red dwarf B 2? planets: Bb?, Bc? Groombridge 34 (11.6191±0.0008 ly) red dwarf B 2 planets: Ab, Ac DX Cancri (11.6797±0.0027 ly) GJ 1061 (11.9839±0.0014 ly) 3 planets: b, c, d YZ Ceti (12.1222±0.0015 ly) 3 planets: b, c, d Luyten's Star (12.3485±0.0019 ly) 2 (4?) planets: b, c, d?, e? Teegarden's Star (12.4970±0.0045 ly) 2 planets: b, c Kapteyn's Star (12.8308±0.0008 ly) Lacaille 8760 (12.9472±0.0018 ly) SCR 1845−6357 (13.0638±0.0070 ly) T-type brown dwarf B Kruger 60 (13.0724±0.0052 ly) red dwarf B DENIS J1048−3956 (13.1932±0.0027 ly) Ross 614 (13.363±0.040 ly) red dwarf B Wolf 1061 (14.0500±0.0016 ly) 3 planets: b, c, d Gliese 1 (14.1747±0.0022 ly) TZ Arietis (14.5780±0.0046 ly) planet b Wolf 424 (14.595±0.031 ly) red dwarf B Gliese 687 (14.8395±0.0014 ly) 2 planets: b, c Gliese 674 (14.8492±0.0018 ly) planet b LHS 292 (14.8706±0.0041 ly)

Degenerate
stars

White dwarfs	van Maanen 2 (14.0718±0.0011 ly)

Brown dwarfs

T-type	UGPS J0722-0540 (13.43±0.13 ly)

← 15–20 ly

Subgiant stars

G-type	Delta Pavonis (19.893±0.015 ly)

Main-sequence
stars

A-type	Altair (Alpha Aquilae) (16.730±0.049 ly)
G-type	Alsafi (Sigma Draconis) (18.7993±0.0081 ly) Achird (Eta Cassiopeiae) (19.3314±0.0025 ly) K-type main-sequence star B e (82 G.) Eridani (19.7045±0.0093 ly) 3 (6?) planets: b, c?, d (c), e?, f?, g?, d
K-type	Groombridge 1618 (15.8857±0.0017 ly) Omicron (40) Eridani (16.3330±0.0042 ly) white dwarf B red dwarf C 70 Ophiuchi (16.7074±0.0087 ly) K-type main-sequence star B Gliese 570 (19.1987±0.0074 ly) 2 red dwarfs: B, C T-type brown dwarf D 36 Ophiuchi (19.4185±0.0036 ly) 2 K-type main-sequence stars: B, C HR 7703 (19.609±0.013 ly) red dwarf B
M-type (red dwarfs)	GJ 1245 (15.2001±0.0034 ly) 2 red dwarfs: B, C Gliese 876 (15.2382±0.0025 ly) 4 planets: d, c, b, e LHS 288 (15.7586±0.0034 ly) GJ 1002 (15.8060±0.0036 ly) 2 planets: b, c Gliese 412 (15.9969±0.0026 ly) red dwarf B AD Leonis (16.1939±0.0024 ly) Gliese 832 (16.2005±0.0019 ly) planet b Gliese 682 (16.3328±0.0026 ly) 2? planets: b?, c? EV Lacertae (16.4761±0.0018 ly) G 9-38 (16.800±0.011 ly) red dwarf B GJ 3379 (16.9861±0.0027 ly) Gliese 445 (17.1368±0.0017 ly) 2M1540 (17.3738±0.0046 ly) GJ 3323 (17.5309±0.0026 ly) 2 planets: b, c Gliese 526 (17.7263±0.0024 ly) Stein 2051 (17.9925±0.0020 ly) white dwarf B Gliese 251 (18.2146±0.0028 ly) planet b LP 816-60 (18.3305±0.0038 ly) LSR J1835+3259 (18.5534±0.0049 ly) Gliese 205 (18.6042±0.0022 ly) Gliese 229 (18.7906±0.0018 ly) T-type brown dwarf B 2 planets: Ab, Ac Ross 47 (18.8883±0.0031 ly) Gliese 693 (19.2078±0.0053 ly) Gliese 754 (19.2724±0.0067 ly) Gliese 908 (19.2745±0.0032 ly) Gliese 752 (19.2922±0.0027 ly) red dwarf B (vB 10) planet Ab Gliese 588 (19.2996±0.0031 ly) 2? planets: b?, c? YZ Canis Minoris (19.5330±0.0040 ly) GJ 1005 (19.577±0.035 ly) red dwarf B Gliese 268 (19.7414±0.0076 ly) red dwarf B

Degenerate
stars

White dwarfs	Gliese 440 (15.1226±0.0013 ly)

Brown dwarfs

L-type	DENIS 0255−4700 (15.877±0.014 ly)
T-type	WISE 1741+2553 (15.22±0.20 ly) WISE 1506+7027 (16.856±0.052 ly) DENIS 0817-6155 (17.002±0.037 ly) 2MASS 0939-2448 (17.41±0.44 ly) T-type brown dwarf B 2MASS 1114-2618 (18.20±0.14 ly) 2MASS 0415-0935 (18.62±0.18 ly) SIMP0136 (19.955±0.057 ly) 2MASS 0937+2931 (19.96 _−0.21 ly)
Y-type	WISE 1639−6847 (15.450±0.041 ly) WISE 0350−5658 (18.49±0.24 ly)

Sub-brown dwarfs
and rogue planets

Y-type	WISE 1541−2250 (19.54±0.24 ly)

Italic are systems without known trigonometric parallax.

Extraterrestrial life

Events and objects

Shergotty meteorite (1865)
Nakhla meteorite (1911)
Murchison meteorite (1969)
Viking lander biological experiments (1976)
Allan Hills 77005 (1977)
Allan Hills 84001 (1984)
Yamato 000593 (2000)
CI1 fossils (2011)

Signals of interest

Misidentified	CP 1919 (misidentified pulsar) CTA-102 (misidentified quasar)
Stars	KIC 8462852 (unusual light fluctuations) EPIC 204278916 (unusual light fluctuations) VVV-WIT-07 (unusual light fluctuations) HD 164595 signal (unknown origin)
Other	SHGb02+14a (radio source) Wow! signal (inconclusive) Fast radio burst (unknown origin) BLC1 (radio signal)

Life in the Universe

Planetary
habitability

Space missions

Interstellar
communication

Types of alleged
extraterrestrial beings

Hypotheses

Fermi paradox solutions

Revision as of 21:02, 30 September 2010

Discovery

Habitability

See also

References

External links