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The Strangest Alien Planets



 The Smallest
    Credit: NASAThis artist's concept of Kepler-10b shows the smallest known exoplanet, announced in January 2011. [Full Story]



The Former ChampCredit: ESO/L. CalcadaGliese 581 e used to hold the title of smallest alien planet. However, it was dethroned in January 2011, with the announcement of Kepler-10b. [Full Story]

The BiggestCredit: Jeffrey Hall, Lowell ObservatoryThe largest exoplanet ever discovered is also one of the strangest and theoretically should not even exist, scientists say. Dubbed TrES-4, the planet is about 1.7 times the size of Jupiter and belongs to a small subclass of so-called puffy planets that have extremely low densities. The planet is located about 1,400 light years away from Earth and zips around its parent star in only three and a half days. [Full Story]

Closest Alien World to UsCredit: NASA, ESA, G.F. Benedict (University of Texas, Austin)Epsilon Eridani b orbits an orange Sun-like star only 10.5 light years away from Earth. It is so close to us telescopes might soon be able to photograph it. It orbits too far away from its star to support liquid water or life as we know it, but scientists predict there are other stars in the system that might be good candidates for alien life. [Full Story]

Volcanic NightmareCredit: ESO/L. CalcadaThis planet, CoRoT-7b, was the first confirmed rocky world outside our solar system, but it doesn't look like a particularly pleasant place to live. It is tidally locked to its parent star, sees hellish 4,000 degrees Fahrenheit (2,200 degrees Celsius). It may also rain rocks and be the core of a vaporized gas giant. [Full Story]

Volcanic NightmareCredit: ESO/L. CalcadaThis planet, CoRoT-7b, was the first confirmed rocky world outside our solar system, but it doesn't look like a particularly pleasant place to live. It is tidally locked to its parent star, sees hellish 4,000 degrees Fahrenheit (2,200 degrees Celsius). It may also rain rocks and be the core of a vaporized gas giant. [Full Story]

Coldest and Farthest From UsCredit: ESOWith a surface temperature of -364 degrees Fahrenheit (-220 degrees Celsius), the extrasolar planet known as OGLE-2005-BLG-390L b is likely the coldest alien world. It is about 5.5 times as massive as Earth and thought to be rocky. It orbits a red dwarf star about 28,000 light-years away, making it the most distant exoplanet currently known. [Full Story]


Hottest WorldCredit: ESA/NASA/Frederic Pont, Geneva University ObservatoryA planet called WASP-12b is the hottest planet ever discovered (about 4,000 degrees Fahrenheit, or 2,200 degrees Celsius), and orbits its star closer than any other known world. It orbits its star one every Earth day at a distance of about 2 million miles (3.4 million km). WASP-12b is a gaseous planet, about 1.5 times the mass of Jupiter, and almost twice the size. It is 870 light-years from Earth. [Full Story]

Super-EarthCredit: ESOAstronomers are finding many worlds now in a category of worlds called Super-Earths, which are between 2 and 10 times the mass of our own Earth. Some scientists think such worlds could be more susceptible to forming the conditions for life because their cores are hot and would be conducive to geological upheaval through volcanism and plate tectonics. [Full Story]

Oldest Alien PlanetCredit: NASA and H. Richer (U. British Columbia)The oldest known planet is a primeval world 12.7 billion years old that formed more than 8 billion years before Earth and only 2 billion years after the Big Bang. The discovery suggested planets are very common in the universe and raised the prospect that life began far sooner than most scientists ever imagined. [Full Story]

The Youngest Known ExoplanetCredit: NASAThe youngest exoplanet yet discovered is less than 1 million years old and orbits Coku Tau 4, a star 420 light-years away. Astronomers inferred the planet’s presence from an enormous hole in the dusty disk that girdles the star. The hole is 10 times the size of Earth’s orbit around the Sun and probably caused by the planet clearing a space in the dust as it orbits the star.
The PuffiestCredit: David A. Aguilar/Harvard-Smithsonian Center for AstrophysicsA planet lighter than a ball of cork is one of the puffiest alien planets known to date. Called HAT-P-1, the planet is about half as massive as Jupiter but about 1.76 times wider-or 24 percent larger than predicted by theory. It could float in water, if there was a tub large enough to hold it. [Full Story]

Fastest PlanetCredit: NASA, ESA, A. Schaller (for STScI)SWEEPS-10 orbits its parent star from a distance of only 740,000 miles, so close that one year on the planet happens every 10 hours. The exoplanet belongs to a new class of zippy exoplanets called ultra-short-period planets (USPPs), which have orbits of less than a day. [Full Story]

WaterworldCredit: David A. Aguilar, CFAThe extrasolar planet GJ 1214b is a rocky planet rich in water that sits about 40 light-years away. It orbits a red dwarf star. It is the only known "Super-Earth" exoplanet — worlds that have masses between Earth and Neptune — with a confirmed atmosphere. The planet is about three times the size of Earth and about 6.5 times as massive. Researchers think it is likely a water world with a solid center. [Full Story]
Atmosphere DetectedCredit: ESA, NASA and G. TinettiAstronomers have been able to detect the atmospheres around several exoplanets, including HD 189733b – one of the first alien words to have its atmosphere sniffed to determine its composition. Glowing methane, which can be produced naturally or be a biological byproduct, has been detected on the planet. [Full Story]
Endangered WorldCredit: CARREAU/ESA/NatureWhen astronomers observed WASP-18b, they may have seen it in the cosmic moment before its death. This planet, possibly an ill-fated world, whips around its star in less than one Earth day. Scientists think that this speed coupled with the planet's heft yields strong gravitational tugs that can alter the planets orbit. If the planet orbits faster than its star spins, it should gradually be moving inward towards its sun, and its doom. [Full Story]
Endangered WorldCredit: CARREAU/ESA/NatureWhen astronomers observed WASP-18b, they may have seen it in the cosmic moment before its death. This planet, possibly an ill-fated world, whips around its star in less than one Earth day. Scientists think that this speed coupled with the planet's heft yields strong gravitational tugs that can alter the planets orbit. If the planet orbits faster than its star spins, it should gradually be moving inward towards its sun, and its doom. [Full Story]

Densest PlanetCredit: ESO/OAMPOne of the densest exoplanet to date is a world known as COROT-exo-3b. It is about the size of Jupiter, but 20 times that planet’s mass, making it about twice as dense as lead. Scientists have not ruled out that the COROT-exo-3b may be a brown dwarf, or failed star. [Full Story]
Diamond PlanetCredit: Swinburne Astronomy ProductionsHere's some bling on an astronomical scale: A Jupiter-mass planet orbiting the newly discovered pulsar PSR J1719-1438 is likely one gigantic diamond. The planet's ultra-high pressure has caused the carbon within it to crystallize into diamond, researchers say. And the weirdness doesn't stop there. The planet was probably once a star, but most of its mass was sucked off by its tiny pulsar companion, which is spinning at a rate of 10,000 revolutions per minute. It is 4,000 light-years from Earth. [Full Story]
Darkest Alien Planet TrES-2bCredit: David A. Aguilar (CfA)The distant exoplanet TrES-2b, shown here in an artist's conception, is darker than the blackest coal. This Jupiter-sized world reflects less than one percent of the light that falls on it, making it blacker than any planet or moon in our solar system. It is 750 light-years from Earth. [Full Story]