Extrasolar planet
hideAn extrasolar planet, or exoplanet, is a planet beyond our Solar System, orbiting a star other than our Sun. As of June 2009[update], 353 exoplanets are listed in the Extrasolar Planets Encyclopaedia. The vast majority have been detected through radial velocity observations and other indirect methods rather than actual imaging. Most announced exoplanets are massive gas giant planets thought to resemble Jupiter, but this is a selection effect (bias) due to limitations in detection technology. Projections based on recent detections of much smaller worlds suggest that lightweight, rocky planets will eventually be found to outnumber extrasolar gas giants.
Extrasolar planets became a subject of scientific investigation in the mid-19th century. Many astronomers supposed that such planets existed, but they had no way of knowing how common they were or how similar they might be to the planets of our Solar System. The first confirmed radial velocity detection was made in 1995, revealing a gas giant planet in a four-day orbit around the nearby G-type star 51 Pegasi. The frequency of detections has tended to increase on an annual basis since then. It is estimated that at least 10% of sun-like stars have planets, and the true proportion may be much higher. The discovery of extrasolar planets sharpens the question of whether some might support extraterrestrial life.
Currently Gliese 581 d, the fourth planet of the red dwarf star Gliese 581 (approximately 20 light years from Earth), appears to be the best example yet discovered of a possible terrestrial exoplanet that orbits within the habitable zone surrounding its star. Although initial measurements suggested that Gliese 581 d resided outside the so-called "Goldilocks Zone", additional measurements place it firmly within.
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News tagged with extrasolar planets
Discovery of a Retrograde or Highly Tilted Extrasolar Planet
Nov 18, 2009 |
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Astronomers have found that the extrasolar planet HAT-P-7b has a retrograde or highly tilted orbit. Studying such planets is important in understanding the diversity of planetary systems and assessing current ...
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Unsettled Youth: Spitzer Observes a Chaotic Planetary System
Nov 04, 2009 |
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(PhysOrg.com) -- Before our planets found their way to the stable orbits they circle in today, they wiggled and jostled about like unsettled children. Now, NASA's Spitzer Space Telescope has found a young ...
Exoplanets Clue to Sun's Curious Chemistry
Nov 11, 2009 |
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(PhysOrg.com) -- A ground-breaking census of 500 stars, 70 of which are known to host planets, has successfully linked the long-standing "lithium mystery" observed in the Sun to the presence of planetary systems. ...
3 Questions: Sara Seager on searching for Earth-like planets
Nov 23, 2009 |
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(PhysOrg.com) -- MIT planetary scientist Sara Seager has been studying exoplanets — planets circling stars other than the sun — for many years.
Starring Intelligent Aliens
Nov 05, 2009 |
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The most probable place to find intelligent life in the galaxy is around stars very similar to our sun, a new study has found.
Kepler Mission Update
Space & Earth / Space Exploration
Nov 06, 2009 |
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(PhysOrg.com) -- Kepler completed another science data download over October 18-19. In this download, a month's worth of science data was transmitted through the NASA Deep Space Network and into the Science ...
SOFIA Seeks Secrets of Planetary Birth
Space & Earth / Space Exploration
Nov 19, 2009 |
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You don't always have to have a rocket to do rocket science. Sometimes a mere airplane will do - that is, a mere Boeing 747 toting a 17-ton, 9-foot wide telescope named SOFIA.
Hunting for Planets in the Dark
Nov 19, 2009 |
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A proposed space mission that aims to measure dark energy could also detect planets that current surveys are unable to find.
Spitzer Telescope Observes Baby Brown Dwarf
Nov 23, 2009 |
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(PhysOrg.com) -- NASA's Spitzer Space Telescope has contributed to the discovery of the youngest brown dwarf ever observed -- a finding that, if confirmed, may solve an astronomical mystery about how these ...
A faraway planet intrigues: Exoplanet with extremely tilted orbit raises new interest in stellar astronomy
Nov 12, 2009 |
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(PhysOrg.com) -- Two teams of astronomers have found a planet outside the solar system that might be orbiting backwards compared to its star's rotation, a discovery that could shed light on how unique the ...
Vatican searches for extra-terrestrial life
Space & Earth / Space Exploration
Nov 10, 2009 |
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Is there life on other planets? The Vatican has asked that age-old question over the past five days during a "study week" on astrobiology gathering leading scientists from around the world.
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