The New Horizons spacecraft may still be several years away from its flyby of the outermost ex-planet, but the Hubble Space Telescope is meanwhile grabbing glimpses of the frozen world at the edge of our solar system.
The video above is composed of hundreds of individual images of Pluto, assembled over the course of four years by the Southwest Research Center in Boulder, CO. It shows the planet’s rotation and differences in coloration around its surface. The most recent images point at changing surface colorations as well, hinting at active atmospheric processes and possibly helping scientists on the New Horizons team target key areas to image in 2015.
The overall color is believed to be a result of ultraviolet radiation from the distant Sun breaking up methane that is present on Pluto’s surface, leaving behind a dark, molasses-colored, carbon-rich residue.
Since its discovery in 1930 Pluto has only traveled 1/3 of its 248-year-long orbit around the Sun. It is 32 times farther away from the Sun than Earth is…from Pluto (and its moons Charon, Nix and Hydra) the
Sun would appear as an extremely bright star in an otherwise dark sky, casting deep shadows in a perpetual frozen twilight. Yet there’s still enough heat to create a dynamic process of freezing and thawing of an atmosphere that spends part of the time as a brittle ground cover and part of the time as a thin haze. Still, at 400º below zero, the term “heat” means something very different than anything we are familiar with.
Animation: NASA/ESA/M. Buie/Southwest Research Institute.