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Extrasolar Planets

An extrasolar planet, or exoplanet, is a planet beyond the Solar System, orbiting around another star. As of December 2008, 333 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 exoplanets are massive gas giant planets thought to resemble Jupiter, but this is a selection effect due to limitations in detection technology. The forthcoming NASA Kepler Mission will search for exoplanets using a completely different technique: planetary transits. 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 581d, the third 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 close to the habitable zone surrounding its star.

  • SIM PlanetQuest Featured Article SIM PlanetQuest SIM PlanetQuest

    SIM (Space Interferometry Mission), scheduled for launch within the next decade, will be the most powerful planet-hunting space telescope ever devised. Using two separated mirrors... More »

  • First Solid Evidence for a Rocky Exoplanet Featured News Article First Solid Evidence for a Rocky Exoplanet First Solid Evidence for a Rocky Exoplanet

    ESO (Sep. 16, 2009) – The longest set of HARPS measurements ever made has firmly established the nature of the smallest and fastest-orbiting exoplanet known, CoRoT-7b, revealing... More »

  • A Little Telescope Goes a Long Way Featured News Article A Little Telescope Goes a Long Way A Little Telescope Goes a Long Way

    PASADENA, CA (Feb. 9, 2010) – NASA astronomers have successfully demonstrated that a David of a telescope can tackle Goliath-size questions in the quest to study Earth-like... More »

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A Little Telescope Goes a Long Way Last Updated on 2010-02-09 17:35:02 PASADENA, CA (Feb. 9, 2010) – NASA astronomers have successfully demonstrated that a David of a telescope can tackle Goliath-size questions in the quest to study Earth-like planets around other stars. Their work, reported today in the journal Nature, provides a new tool for ground-based observatories, promising to accelerate by years the search for prebiotic, or life-related, molecules on planets orbiting stars beyond our solar system. FIGURE CAPTION – This artist concept shows the planetary system called HD 189733, located 63 light-years away in the constellation Vulpecula. Image credit: NASA/JPL-Caltech The scientists reported on a new technique used with a relatively small Earth-based telescope to identify an organic molecule in the atmosphere of a Jupiter-size planet nearly 63 light-years away. The measurement revealed details of the exoplanet's atmospheric composition... More »
NASA's Kepler Space Telescope Discovers Five Exoplanets Last Updated on 2010-01-05 00:00:00 PASADENA, CA (Jan. 4, 2010) – NASA's Kepler space telescope, designed to find Earth-size planets in the habitable zone of sun-like stars, has discovered its first five new exoplanets, or planets beyond our solar system. Kepler's high sensitivity to both small and large planets enabled the discovery of the exoplanets, named Kepler 4b, 5b, 6b, 7b and 8b. The discoveries were announced Monday, Jan. 4, by members of the Kepler science team during a news briefing at the American Astronomical Society meeting in Washington. "These observations contribute to our understanding of how planetary systems form and evolve from the gas and dust disks that give rise to both the stars and their planets," said William Borucki of NASA's Ames Research Center in Moffett Field, Calif. Borucki is the mission's science principal investigator. "The discoveries also show that our... More »
In All the Universe, Just 10 Percent of Solar Systems Are Like Ours Last Updated on 2010-01-05 00:00:00 WASHINGTON, DC (Jan. 5, 2010) – In their quest to find solar systems analogous to ours, astronomers have determined how common our solar system is. They’ve concluded that about 15 percent of stars in the galaxy host systems of planets like our own, with several gas giant planets in the outer part of the solar system. FIGURE CAPTION – The planets are shown in the correct order of distance from the Sun, the correct relative sizes, and the correct relative orbital distances. The sizes of the bodies are greatly exaggerated relative to the orbital distances. The faint rings of Jupiter, Uranus, and Neptune are not shown. Eris, Haumea, and Makemake do not appear in the illustration owing to their highly tilted orbits. The dwarf planet Ceres is not shown separately; it resides in the asteroid belt between Mars and Jupiter. (Credit: NASA) “Now we know our place in the... More »
Avatar's Moon Pandora Could Be Real Last Updated on 2009-12-18 00:00:00 CAMBRIDGE, MA (Dec. 18, 2009) – In the new blockbuster Avatar, humans visit the habitable - and inhabited - alien moon called Pandora. Life-bearing moons like Pandora or the Star Wars forest moon of Endor are a staple of science fiction. With NASA's Kepler mission showing the potential to detect Earth-sized objects, habitable moons may soon become science fact. If we find them nearby, a new paper by Smithsonian astronomer Lisa Kaltenegger shows that the James Webb Space Telescope (JWST) will be able to study their atmospheres and detect key gases like carbon dioxide, oxygen, and water vapor. FIGURE CAPTION – This artist's conception shows a hypothetical gas giant planet with an Earth-like moon similar to the moon Pandora in the movie Avatar. New research shows that, if we find such an "exomoon" in the habitable zone of a nearby star, the James Webb Space... More »
First Direct Observation of a Planet-like Object Orbiting a Star Similar to the Sun. Last Updated on 2009-12-03 16:48:38 PRINCETON, NJ (Dec. 3, 2009) – An international team of scientists that includes an astronomer from Princeton University has made the first direct observation of a planet-like object orbiting a star similar to the sun. The finding marks the first discovery made with the world's newest planet-hunting instrument on the Hawaii-based Subaru Telescope and is the first fruit of a novel research collaboration announced by the University in January. The object, known as GJ 758 B, could be either a large planet or a "failed star," also known as a brown dwarf. The faint companion to the sun-like star GJ 758 is estimated to be 10 to 40 times as massive as Jupiter and is a "near neighbor" in our Milky Way galaxy, hovering a mere 300 trillion miles from Earth. "It's a groundbreaking find because one of the current goals of astronomy is to directly detect... More »