According to a recent research, Pluto’s gases are disappearing and reverting back into ice as it moves farther away from the Sun.
(Photo : NASA, John Hopkins University Applied Physics Laboratory, Southwest Research Institute)
Pluto’s atmosphere, which is already thin, is mostly nitrogen, with a few dabs of methane and carbon monoxide thrown in for good measure. However, as the temperature on the surface drops, nitrogen appears to be freezing up again, causing the atmosphere to fade.
The evaluation was done via occultation, which involves utilizing a distant star as a backlight for Earth-based telescopes to look at what’s going on on Pluto. It’s a tried-and-true observation method extensively employed in astronomy.
Monitoring Pluto’s Atmosphere
(Photo : Figures created using images by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.)
Since 1988, planetary scientist Eliot Young of the Southwest Research Institute (SwRI) in Texas has utilized occultations to monitor changes in Pluto’s atmosphere.
“The New Horizons mission got an excellent density profile from its 2015 flyby, which is consistent with Pluto’s bulk atmosphere doubling every decade, but our 2018 measurements do not support that pattern.”
Pluto’s atmosphere is made up of evaporated ice on the surface, with slight temperature variations causing substantial changes in the atmosphere’s bulk density. Sputnik Planitia, located in the western portion of Pluto’s heart-shaped Tombaugh Regio region, is the world’s biggest known nitrogen glacier.
The dwarf planet presently takes 248 Earth years to complete one circuit around the Sun, approaching the Sun as near as 30 astronomical units (AUs) – 30 times the distance between Earth and the Sun – at one point.
However, as the distance between Pluto and the Sun grows, Pluto receives less sunlight and experiences colder temperatures. Thermal inertia – excess heat trapped in the nitrogen glaciers that has a delayed reaction to the growing distance between Pluto and the Sun – is most likely to blame for the increase in atmospheric density seen in 2015.
According to SwRI planetary scientist Leslie Young, “one analog to this is how the Sun warms up sand on a beach.” “The sun is brightest around high noon, but the sand continues to absorb the heat throughout the day, so it is warmest in the late afternoon.”
(Photo : Kamata S. et al., Pluto’s ocean is capped and insulated by gas hydrates. Nature Geosciences, May 20, 2019.)
Pluto may no longer be considered a planet – a point of contention among scientists – but it is still a planetary entity of interest to astronomers. As a result, we continue to discover new things about this faraway rock regularly.
Astronomers have just discovered that Pluto has snowcapped mountains and liquid seas under its surface, two findings that might help us learn more about how the dwarf planet’s atmosphere works (and both coming as a result of the 2015 New Horizons flyby).
The 2018 observations were aided by a ‘central flare,’ suggesting that the telescopes pointed directly at Pluto as atmosphere data were taken, bolstering their reliability.
According to Young, “the center flare observed in 2018 was by far the strongest anybody has ever seen in a Pluto occultation.” “The center flare provides us with highly precise information on Pluto’s shadow path on Earth.”
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