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04-03-09 The lower atmosphere of Pluto revealed

By observing stellar occultations,astronomers were able to demonstrate that Pluto's upper atmosphere was some 50° warmer than the surface.Astronomers have gained valuable new insights about the atmosphere of the dwarf planet Pluto.Using European Southern Observatory's (ESO) Very Large Telescope (VLT),the scientists found unexpectedly large amounts of methane in the atmosphere,and they also discovered that the atmosphere is hotter than the surface by about 40°,although it still only reaches a frigid -356° Fahrenheit (-180° Celsius).These properties of Pluto's atmosphere may be due to the presence of pure methane patches or of a methane-rich layer covering the dwarf planet's surface."With lots of methane in the atmosphere, it becomes clear why Pluto's atmosphere is so warm," said Emmanuel Lellouch,lead author of the paper reporting the results.It has been known since the 1980s that Pluto also has a tenuous atmosphere that consists of a thin envelope of mostly nitrogen,with traces of methane and probably carbon monoxide.As Pluto moves away from the Sun,during its 248-year-long orbit,its atmosphere gradually freezes and falls to the ground.In periods when it is closer to the Sun - as it is now - the temperature of Pluto's solid surface increases,causing the ice to sublimate into gas