Saturday, April 14, 2012

Earth Size Planets in Red Dwarf Habitable Zone are Like Venus

The Earth in the midel of our sun’s habitable zone this is the range of distances around a star at which planets can have liquid water on their surface. Astronomers have found that about 40% of red dwarfs have approximately Earth size planets orbiting them and that many of these are within the stars habitable zone. This fact has lead to suggestions that these planet could have life on them. However a new study shows that tidal forces may dry out Earth size planets orbiting within a red dwarf “habitable zones” making them more like Venus than Earth and therefore hostile to life.

Red dwarfs are cooler and fainter than the sun so as a reult a planet orbiting within a red dwarf's “habitable zones” would be  closer to the star than the Earth is to the Sun. This also means that such planets would have a very strong tidal force with the star so that if the planet is not in a perfectly circular orbit it would get stretched and squeezed as this pull changes during the planets orbit heating the planet up. As result a planet with liquid water orbiting a star whose mass is less than 1/3 that of the sun would get so hot that its water would evaporate. The light from the star would split the water vapor into hydrogen and oxygen. The Hydrogen would escape into space and the oxygen would combine with carbon to form carbon dioxide thus producing a Venus like planet.

The result is that so called Earth like planets orbiting red dwarf stars are hardly Earth like. These planets are more like Venus and totally hostile to life. This study showsfurther evidience of how unique our solar system and the Earth are.


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