Pluto lies in the Kuiper Belt, a donut-shaped region of icy bodies beyond the orbit of Neptune. Smaller than Earth’s Moon, Pluto has a heart-shaped glacier of the size of Texas and Oklahoma. It has fascinating world with blue skies, spinning moons, the Rockies high mountains, and red snow. On July 14, 2015, New Horizons Spacecraft of NASA made its historic flight through the Pluto system, which provided the first close-up images of Pluto and its moons and also collected other data that transformed our understanding of the planet.
The time taken by Pluto to complete a single orbit of the Sun is 248 Earth-years. Its distance varies from its closest point from about 30 astronomical units (AU) to 50 AU from the sun (1 AU is the distance from the Earth to the Sun.) In 2006, Pluto was categorised as a dwarf planet. This long orbit and its distance from the Sun mean that the surface temperature of Pluto is between minus –378 and –396 degrees Fahrenheit. Pluto’s atmosphere is already on the thin side and is made up of nitrogen, methane, and carbon monoxide. This is causing Pluto’s atmosphere to fade. Now the scientists have revealed that by 2030, Pluto’s atmosphere may completely collapse and freeze, due to changes that are causing its atmosphere to disappear.
Pluto’s Occultation of a Star
On August 15, 2018, Pluto passed in front of a star for two minutes. That event backlit Pluto’s atmosphere. Thereafter, research was carried out by the scientists at Southwest Research Institute (SwRI) Scientists knew that as Pluto and its atmosphere were backlit by the star, a faint shadow of Pluto would move across Earth’s surface. The centre line of this shadow path ran from Baja and California, up to Delaware. Telescopes were deployed along the shadow path to study Pluto during this occurrence. For two minutes, the light of the background star diminished as it passed behind Pluto’s atmosphere. The star again emerged on Pluto’s other side.
Findings of the Study
The detailed study of this occurrence by the scientists stated that Pluto was moving farther away from Sun. Pluto’s atmosphere was actually refreezing back onto its surface and the planet was getting colder and colder. Pluto’s surface pressure and atmospheric density had been increasing due to a phenomenon known as thermal inertia. Its icy surface and nitrogen atmosphere were supported by the vapour pressure, a tendency of ice to change to a gaseous state as the temperature increases. When Pluto came nearest to the sun between 1979 and 1999, the temperature of its surface ices had warmed, giving a rise to the planet’s atmosphere from its surface.
Pluto’s Atmosphere and Its Orbit
Astronomers on Earth first discovered Pluto’s atmosphere in 1988 during an occultation of a star by Pluto. Then, Pluto was considered the ninth planet in our solar system. During this event, the light of the passing star dimmed gradually before disappearing behind Pluto. The dimming of the star demonstrated the presence of Pluto’s thin, and greatly distended atmosphere. Since then, international collaboration of scientists from eight countries had been studying Pluto’s atmosphere.
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