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Gliese 581 c (pronounced /ˈɡliːzə/) or Gl 581 c is an extrasolar planet orbiting the red dwarf star Gliese 581.[2] With a mass at least 5.36 times that of the Earth, it is classified as a super-Earth, a category which incorporates planets exceeding the mass of Earth but smaller than 10 Earth masses.[3] Assuming that the planet's mass is close to the lower limit determined by radial velocity measurements (the true mass is unknown), it was the smallest known extrasolar planet around a main sequence star, but on April 21, 2009, another planet orbiting Gliese 581, Gliese 581 e, was announced with an approximate mass of 1.9 earth masses, which is now the smallest known extrasolar planet around a main sequence star.[4]
