Sayonara, Pluto! This image was captured by NASA’s New Horizons spacecraft from 1.25 million miles away on July 15th, immediately following its flyby of the dwarf planet. Pluto appears in silhouette, backlit by the Sun, while the white outline is the haze in Pluto’s atmosphere, which has been revealed by New Horizons to be several times thicker than previously estimated. In fact, there are two distinct levels of haze visible in the new images, one at 30 miles above Pluto’s surface and another at 50 miles above.
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.
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–within the last 10s of millions of years–and may still be doing so today. So far, evidence of this phenomenon has only ever been observed on Earth and Mars. “From what we know of the heat flow coming from interior, there’s no reason that this stuff cannot be going on today,” said New Horizons’ Bill McKinnon.
Images of Pluto’s surface captured by NASA’s New Horizons spacecraft reveal that a giant sheet of ice recently flowed — and could still be flowing now — in a plain in the western half of Pluto’s “heart,” also known as Tombaugh Regio.
The image shows an area that’s about 250 miles across. It shows evidence of deep and extensive erosion, while the top shows evidence of a viscous ice flow filling in a crater. “The plains seem to have moved and surrounded the mountains,” said McKinnon. “To see evidence of recent geological activity is a dream come true.”
Flowing Ices On Pluto
You can fly over Sputnik Planum in this NASA video:
Our map of Pluto is starting to get pretty detailed now:
Among the many fun new names given to features of Pluto’s landscape that were revealed by NASA’s New Horizons spacecraft is an especially eye-popping one: Cthulhu, the name given to the dark, heavily-cratered region on Pluto’s southern hemisphere and a reference to the fictional ancient, squid-faced “Elder God” deity created by sci-fi writer H.P. Lovecraft.
A global mosaic of Pluto captured by NASA’s New Horizons spacecraft and released on July 24 reveals Pluto and its distinctive heart-shaped feature in more eye-popping detail than ever captured. The image was created by combining four separate captures from the Long Range Reconnaissance Imager (LORRI) with color data from the Ralph Instrument on New Horizons, and contains twice the amount of detail compared to the view captured on July 13.