Pluto’s atmospheric pressure on its surface is 80,000 times less than that on Earth, a study by a team of researchers from India, Brazil, and France has revealed.
They observed a stellar occlusion — a phenomenon where the planet coming in front of a bright star is viewed from Earth — on June 6, 2020, through a 3.6m Devasthal optical telescope and 1.3m Devasthal Fast Optical Telescope in Nainital.
The researchers studied the signal-to-noise ratio of the light curves to arrive at the accurate atmospheric pressure of Pluto. The atmospheric pressure of Pluto was found to be 12.23 μbar, which is over 80,000 times less than the pressure present on Earth.
The research, which has been published in the Astrophysical Journal Letters, also shows that the pressure is less when it is close to the seasonal peak. There is seasonal variability in Pluto’s atmospheric pressure due to the vapour pressure from the nitrogen ice. Moreover, the poles of the dwarf planet remain in permanent sunlight or permanent darkness for decades during its 248-year-long orbit around the sun.
A compilation of twelve stellar occlusions by Pluto observed between 1988 and 2016 showed a three-fold steady increase in atmospheric pressure during this period. The atmospheric pressure on the dwarf planet had plateaued close to the peak since 2015, the researchers said in their paper. “It is in excellent agreement with the model values calculated earlier by the Pluto volatile transport model in 2019,” a release from the department of science read.
The study also pointed that the occlusion was seen as the dwarf planet is moving away from the galactic plane visible from Earth, making stellar occlusions rarer.
The team included researchers from Aryabhatta Research Institute of Observational Sciences-Uttarakhand, Physical Research Laboratory-Ahmedabad, and Indian Institute of Space Science and Technology-Thiruvanathpuram from India.