YOW! Pluto STUNS boffins with HAZY, SHRINKY atmosphere

Probe spots nitrogen ice glaciers flowing into craters

Pluto bumper sticker
See this sticker on a car and you're driving behind a NASA bod

Pics and vid The latest New Horizons data blurt from the Kuiper Belt has yet again left astroboffins' flabbers gasted, this time because of its sensational revelations regarding the atmosphere of frosty freezeworld Pluto.

Details about the dwarf planet's extraordinary surface have also been revealed by NASA, with flowing nitrogen ice glaciers carving out new features on Pluto.

"We knew that a mission to Pluto would bring some surprises, and now – 10 days after closest approach – we can say that our expectation has been more than surpassed," said John Grunsfeld, the US space agency's associate administrator for the Science Mission Directorate.

"With flowing ices, exotic surface chemistry, mountain ranges, and vast haze, Pluto is showing a diversity of planetary geology that is truly thrilling."

The team published the first photo of Pluto being backlit from the Sun as the New Horizons probe speeds away from the freezeworld. The image clearly revealed a hazy ring of atmosphere around Pluto, but data from the probe shows that it is highly unusual and appears to be responsible for its reddish tinge.

Pluto backside

Pluto from behind ... Wish my arse looked this good

We already know that Pluto's atmosphere is larger than expected, extending at least 100 miles above the surface. Now, new data shows that it's also hazy: suspended hydrocarbons are formed when ultraviolet solar rays break down the methane in the atmosphere to form new substances.

These hydrocarbons eventually clump up into a haze and fall as red rain onto the surface. If you were to stand on the surface of Pluto the haze is thin enough to be almost unnoticeable, but New Horizons' instruments managed to pick it up.

But the atmosphere has NASA boffins in a tizzy for another reason – its low pressure. When New Horizons whizzed past Pluto, two dishes from NASA's Deep Space Network fired a pulse of radio waves at the probe so that their refraction through Pluto's atmosphere could be collected, revealing the surface pressure.

We've taken measurements of Pluto's surface pressure before, by watching the readings as it passes in front of other suns. The new data shows the surface pressure at the moment is about 1/100-thousandth of the pressure of Earth at sea level, which wasn't expected at all.

Because Pluto has such a distant and elliptical orbit around the Sun (each year lasts 248 Earth years) it was thought that the atmosphere would diminish as it moves away from our star. This is because the atmosphere is fed by gases sublimating from the surface in the Sun's heat.

The unexpectedly low reading led to speculation that we might be seeing that in action now that Pluto is moving away from the Sun. But it's not cut and dried.

"Nitrogen should be condensing and thus Pluto's mass increasing, but instead we're seeing the exact opposite," said Michael Summers, New Horizons co-investigator at George Mason University.

"We saw the surface pressure at most 10 microbars, so the mass decreased by a factor of two in the two years since the last measurement – that's pretty astonishing."

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