Are We Really Lonely In Space - Gliese 581e

By Author: dotstan
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Gliese 581e is the fourth satellites discovered so far around the M3V-type red dwarfs Gliese 581. This extrasolar planet is located in Libra, about 20.5 light years from Earth. It's at least 1.9 times Earth in mass, and the smallest extrasolar planet discovered so far with a nearest mass to Earth. However, its orbit from the parent star is only 0.03 astronomical units, away from the habitable zone; in the meantime due to high temperature, too small size and the strong radiation from the star, it is unlikely to have an atmosphere.

Gliese 581e was discovered by the Geneva Observatory's astronomer Michel Mayer and his team, using the High Accuracy Radial Velocity Planet Searcher (HARPS) at the Observatorio de La Silla in Chile. The team announced the discovery at a press conference at University of Hertfordshire in April 21 2009 that demonstrated "a progress in finding terrestrial planets". One of Michel's rivals, Geoffrey W Marcy, Professor of Astronomy at University of California, praised the discovery as "especially brilliant". "It's an important step. It shows that planets in near size can be formed naturally. Ant these ...
... similar planets may massively exist outside the solar system."

Michel's team used a technique of radial velocity, which determines under the action of universal gravitation the orbit and size of the planet by measuring the small perturbation of the parent star's orbit.

Gliese 581e is the smallest of 350 extrasolar planets ever found. Its proper size means that it may be a terrestrial planet full of rocks, not like Jupiter or Saturn which are filled with gas.

Unlike Gliese 581c, which is in the same line of galaxy and may have lives, 581e's orbital period is only around 3.15 days, which means its orbit is very close to the parent star Gliese 581. It is almost certainly a hot planet, outside the habitable zone, and so life cannot be conceived as like the earth.

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