Five years ago NASA were baffled with Earth’s shrinking atmosphere
Large changes in the sun’s energy output may drive unexpectedly dramatic fluctuations in Earth’s outer atmosphere.
Results of a study published today link a recent, temporary shrinking of a high atmospheric layer with a sharp drop in the sun’s ultraviolet radiation levels.
The research, led by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., and the University of Colorado at Boulder (CU), indicates that the sun’s magnetic cycle, which produces differing numbers of sunspots over an approximately 11-year cycle, may vary more than previously thought.
New Horizons has only taken a snapshot in time so we are unlikely to know if the current low solar activity may be linked to Pluto’s shrunken atmosphere [my emphasis].
From previous observations, scientists assumed the pressure on Pluto’s surface would be about 15 microbars, but it turned out they were wrong, by quite a bit.
This REX occultation data says that the pressure on Pluto’s surface is just 7 microbars. It could be that the atmosphere is kind of collapsing, that the atmosphere, the gases that make up that atmosphere, are freezing and falling to the surface. If this is what’s happening, it’s possible that the collapse of Pluto’s atmosphere is imminent, or at least that most of the gas in the atmosphere will freeze and fall to the surface.
Before arriving in the Pluto system, a lot of scientists assumed that Pluto’s moon Charon would be pretty much an uninteresting cratered body not unlike the planet Mercury. Earth-based observations show there was no atmosphere on the moon, so there was little hope of something interesting like resurfacing going on.
But when New Horizons returned the first ever close-up, detailed images of Charon’s surface, it turned out scientists were wrong. Charon is absolutely fascinating and it makes the story a little more interesting.
Charon is heavily cratered like you would expect a body in the Kuiper belt to be. But it also has chasms and craters marking its surface. And they’re not small, either. The most pronounced chasm lies in the southern hemisphere, and it is miles longer and deeper than the Grand Canyon in Arizona. There are prominent craters up to 60 miles across and the ejecta pattern of some of these craters is puzzling. You’d think that what’s blasted out of the crater would be the same thing as what’s inside the crater, but on Charon that doesn’t necessarily seem to be the case. There are also areas on Charon’s surface that are remarkably smooth, suggesting that something has resurfaced them in recent history.
I’m not convinced by the explanations, or rather assumptions, given so far to explain Charon’s stunning features [emphasis added]¬¬.
A swath of cliffs and troughs stretches about 600 miles (1,000 kilometers) from left to right, suggesting widespread fracturing of Charon’s crust, likely a result of internal processes. At upper right, along the moon’s curving edge, is a canyon estimated to be 4 to 6 miles (7 to 9 kilometers) deep.
Mission scientists are surprised by the apparent lack of craters on Charon. South of the moon’s equator, at the bottom of this image, terrain is lit by the slanting rays of the sun, creating shadows that make it easier to distinguish topography. Even here, however, relatively few craters are visible, indicating a relatively young surface that has been reshaped by geologic activity.
In Charon’s north polar region, a dark marking prominent in New Horizons’ approach images is now seen to have a diffuse boundary, suggesting it is a thin deposit of dark material. Underlying it is a distinct, sharply bounded, angular feature; higher resolution images still to come are expected to shed more light on this enigmatic region.