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Pluto may be undergoing global warming

The Hubble Space Telescope's view of Pluto, left, and its moon Charon
The Hubble Space Telescope's view of Pluto, left, and its moon Charon  

By Richard Stenger

(CNN) -- Pluto could be experiencing a warming trend on the surface and a cooling trend in the atmosphere, according to planetary scientists.

Astronomers made the deduction based on observations of a recent stellar eclipse when Pluto passed in front of the light of star P126A.

When the planet eclipsed another star in 1998, the starlight went out quickly. During the July event, the light dimmed slowly as Pluto passed in front.

By studying the starlight, scientists estimated the density, pressure and temperature of Pluto's atmosphere.

"In the last 14 years, one or more changes have occurred," said Marc Buie of Lowell Observatory in Flagstaff, Arizona. "Pluto's atmosphere is undergoing global cooling, while other data indicates that the surface seems to be getting slightly warmer.

"Change is inevitable as Pluto moves away from the sun, but what we're seeing is more complex than expected," said Buie, who with James Elliot of the Massachusetts Institute of Technology reported the findings last week.

Pluto has a highly eccentric orbit and is heading away from the sun to the most distant point in its travels.

Astronomers theorize that during such times Pluto's atmosphere freezes over for more than a century.

The scientists will be able to get more data when Pluto passes in front of another star Tuesday.

Such star eclipses or occultations are taking place more frequently because Pluto is moving in line with the main band of the Milky Way, where stars are more commonplace.




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