Is Pluto’s atmosphere collapsing as predicted?
Pluto as seen by New Horizons in 2015. The frozen nitrogen
ocean, Sputnik Planitia, is the light-colored smooth area.
Click for original image.
Astronomers, using data from the ten times Pluto passed in front of a star during the period from 2017 to 2023, now believe that its thin atmosphere has begun to condense as expected as the planet moves outward away from the Sun.
You can read their paper here [pdf]. From the press release:
In a new paper published in the Planetary Science Journal, Sickafoose and her team describe how Pluto’s atmosphere changed over the 2017-2023 timeframe. They found that between the 2015 New Horizons flyby and part way through 2021, Pluto’s atmospheric pressure remained constant. Then, between mid 2021 and July 2023, the bulk pressure decreased by 16%. Their models assumed a hazy atmosphere, as was seen during the Pluto flyby.
Pluto’s atmosphere was first discovered by stellar occultation studies in the late 1980s. At that time it was predicted the atmosphere would completely condense out once Pluto reached the farthest and coldest point from the Sun. The discovery of the vast nitrogen sea Sputnik Planitia by New Horizons during its close fly-by in 2015 however has caused some scientists to predict the atmosphere will not completely condense, though its thickness is still expected to decline. This new paper fits both theories. It is still too soon to know what will happen.
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It may very well be that NH came by at an opportune time… stratification visibility highest during its visit perhaps
The plan for New Horizon was to fly by Pluto while it had an atmosphere. It was proposed in the 1990s and sold as the only opportunity to investigate Pluto’s atmosphere, at least for the next two centuries. Waiting too long would miss this opportunity until Pluto gets close to the Sun again (“close” is a relative term).
It could be interesting to do another flyby in a few decades to see what the differences are with the atmosphere condensed onto the surface.
My Earth-centric mind sees Sputnik Planitia as Antarctica, giving the planet (yeah, I said it) the appearance of laying on it’s side, Uranus-like. It takes a quick mental adjustment to orient correctly.
You don’t have to apologize for calling Pluto a Planet. It is the Ninth Planet. It was found as a direct result of the search for the ninth planet. It has enough gravity to pull itself into s sphere. It has Moons and it has an atmosphere. All that, in my book, makes it a Planet. It certainly has a heck of a lot more to qualify it as a Planet than some of the glorified asteroids that have been nominated by the stellar revisionists.