Pluto Has "Upside Down" Atmosphere

Pluto, the solar system's oddball, has an upside-down atmosphere compared with Earth. Temperatures rise, rather than drop, with altitude on the dwarf planet, a new study finds.

Astronomers recently made the most detailed measurements to date of the concentration of the greenhouse gas methane in Pluto's atmosphere using the European Southern Observatory's Very Large Telescope.

The measurements showed that methane is the second most abundant gas in Pluto's atmosphere, and that the gas is actually warmer at higher elevations than at the icy surface.

As a result, Pluto's upper atmosphere is about 90 degrees Fahrenheit (50 degrees Celsius) warmer than the planet's surface.

The team, led by Emmanuel Lellouch of France's Paris Observatory, speculates that there is a thin frozen layer, or frozen patches, of methane and other gases on Pluto's surface.

As Pluto orbits closer to the sun, the frozen gases vaporize. This process, called sublimation, cools Plutos surface while warming the planet's atmosphere.

via Pluto Has "Upside Down" Atmosphere.