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The smallest planet known outside our solar system found

Astronomers on Wednesday announced the discovery of what is possibly the smallest planet known outside our solar system orbiting a normal star.

 Its orbit is farther from its host star than Earth is from the sun. Most known extrasolar planets reside inside the equivalent of Mercury’s orbit. The planet and star are separated by about 2.5 astronomical units. One AU is equal to the distance between the Earth and the sun. Until now, no small planet had been found farther than 0.15 AU from its parent star.

 The planet is estimated to be 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. Earth-sized planets have been detected, but only around dying neutron stars.

 With a surface temperature of 364 degrees below zero Fahrenheit (-220 degrees Celsius), the newfound planet, named OGLE-2005-BLG-390Lb, is probably too cold to support life as we know it, astronomers said.

 It was discovered using a technique called "gravitational microlensing," whereby light from a distant star is bent and magnified by the gravitational field of a foreground star. The presence of a planet around the foreground star causes light from the distant star to become momentarily brighter.

posted by: kyawoo at 19:46 | link | comments |
astronomy

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