But more exciting than seeing changes in the Plutonian atmosphere is its possible shape.
Pluto's atmosphere, as seen in UV light - the sun appears blue in this image (P.A.S. Cruickshank).
When analyzing the spectrum of the light reflected from this extended CO atmosphere, Greaves' team spotted something odd. There's a slight redshift in wavelength, indicating that the bulk of the gas is moving away from the Earth. Although the results are preliminary, Greaves has a theory.
"The marginal CO line red-shift, if real, could indicate a ﬂow forming into a comet-like tail directed away from the Sun," she said.
Even though Pluto patrols the outermost region of the solar system, even this little world isn't immune to the ravages of the solar wind, potentially turning it into a "comet dwarf."
"Seeing such an example of extra-terrestrial climate-change is fascinating", said Greaves. "This cold simple atmosphere that is strongly driven by the heat from the Sun could give us important clues to how some of the basic physics works, and act as a contrasting test-bed to help us better understand the Earth's atmosphere."