Beamed across billions of miles and a very narrow bandwidth, the latest images from the Pluto flyby were worth waiting for. One reveals the view from New Horizons after it sped past Pluto and looked back to study its atmosphere. “This is our equivalent on New Horizons of the Apollo 11 earthrise,” says New Horizons' Alan Stern.
It is both beautiful and mysterious. Backlighting by the sun shows that Pluto's atmosphere is about four times taller than scientists thought was possible. It has two distinct layers of haze--one at 30 miles above the surface, and another at 50 miles. The haze extends to about 80 miles out, whereas scientists previously thought that it could only extend to 20 miles.
From a NASA press release:
Models suggest that the hazes form when ultraviolet sunlight breaks apart methane gas, a simple hydrocarbon known to reside throughout Pluto's atmosphere. The breakdown of methane triggers the buildup of more complex hydrocarbon gases, such as ethylene and acetylene, which were also discovered at Pluto by New Horizons. As these hydrocarbons fall to the lower, colder parts of the atmosphere, they condense as ice particles, forming the hazes. Ultraviolent sunlight chemically converts hazes into tholins, the dark hydrocarbons that color Pluto's surface.
Another image suggests that ice sheets have scraped across Pluto's "Sputnik Plains" sometime in recent history. So far, evidence of this phenomenon has only ever been observed on Earth and Mars.
Ice appears to have flowed and may still be flowing across the Texas-sized plains in the Western part of Pluto's "heart". These are just the latest data that dispel the idea that Pluto is "dead"--it is in fact a world that's geologically alive.
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