Pluto's atmosphere is collapsing as it drifts away from the sun into a deep freeze

Pluto's atmosphere appears to be freezing out as the dwarf planet moves ever further away from the sun, according to careful observations of Pluto astronomers made as it was seen passing in front of stars in the sky.

Pluto is already cold. Its surface temperature is about –382 degrees Fahrenheit (–230 degrees Celsius), while its upper atmosphere is a little warmer at –333 degrees Fahrenheit (–203 degrees Celsius). As Pluto moves away from the sun it will grow even colder and its nitrogen-rich atmosphere should start to collapse and freeze out, condensing as frost on the frigid surface.

Now, a team led by Amanda Sickafoose of Arizona's Planetary Science Institute believe they have seen the onset of this process. "We're at a particularly interesting point for Pluto," said Sickafoose in a statement. "Our work suggests that the atmosphere has recently started decreasing in pressure."