There is a spherical body in our solar system, who was once a hero to everyone with the title of “the smallest planet in the solar system”. Yeah, Pluto.
Pluto holds its title till 2006. The aspiration to unleash the secrets of our solar system paved the way to study this distant neighbour. For that, NASA got the best adventurer spacecraft, New Horizons. To take humanity to the new horizon of wonder and knowledge, this adventurer started his long journey in 2006 by holding the ashes of Clyde William Tombaugh. After a decade long journey, on July 14, 2015, New Horizons made its closest approach to Pluto. New Horizons thereby made a new chapter in the history of space exploration. It became the 1st first spacecraft to reach Pluto and the 2nd to fly by and study one or more other Kuiper belt objects (KBOs) in the decade to follow. Last year, on January 1, 2019, spacecraft made its closest approach to 486958 Arrokoth– you may know this object in another name as “Ultima Thule”.
It became the 5th space probe to attain the escape velocity needed to leave the Solar System.
Few months after the launch of New Horizon, that shocking news arrived. IAU classified pluto as a dwarf Planet and taken away its title of ‘Planet’ in September 2006. According to IAU, there are three conditions for an object in the Solar System to be considered a planet:
- The object must be in orbit around the Sun.
- The object must be massive enough to be rounded by its own gravity. More specifically, its own gravity should pull it into a shape defined by hydrostatic equilibrium.
- It must have cleared the neighbourhood around its orbit.
Pluto was unable to meet the 3rd criteria. Very sad and heartbreaking announcement from the International Astronomical Union. Many of the scientists in the team behind New Horizon still disagree with this declaration. They still believe and consider Pluto as the 9th planet. Even at the moment when the whole world calls Pluto a dwarf planet, the entire team was sure that a simple name was not gonna make this planet inconsequential.
There are many mysteries about pluto yet to be understood by humanity. The desire to uncover these secrets made the science community to conduct many more observations and missions.
New Horizon has a friend in Earth to help him in detailed observation. This friend of New Horizon is none other than the flying Telescope, SOFIA, the Stratospheric Observatory for Infrared Astronomy. At the time when New Horizon was doing his adventure flyby and observations, SOFIA did its observation from Earth. The combined Data received from SOFIA and New Horizon helped scientist to uncover a new secret of Pluto.
From the observation of these two missions, NASA discovered a hazy atmosphere in Pluto. It was an unbelievable observation about the frozen world which is at an average distance of 5,906,380,000 kilometres from Sun. Finally, It is found that this haze atmosphere is formed when the dim light from the sun gets scattered by the tiny particles on the atmosphere of Pluto. These particles can stay on the atmosphere for many years and the thickness of this haze is varying according to the position of Pluto from Sun.
Sunlight takes 5 hours to reach Pluto. When light falls on the surface of Pluto, the Icy rich region get evaporated and the tiny particles formed and they expand to the atmosphere. Pluto’s atmosphere is predominantly nitrogen gas, along with small amounts of methane and carbon monoxide. When the pluto reach the colder region, the formation of these particle and thickness reduces but does not fade away completely.
Credits: NASA/JHUAPL/SwRI
New Horizon studied the upper and lower layer of the atmosphere by observing the Radio waves and Ultraviolet rays; at the same time, SOFIA observed the middle layer. From the observation of SOFIA, NASA found that Pluto has a particle extremely small, just 0.06-0.10 microns thick, or about 1,000 times smaller than the width of a human hair. Since the particle is this much small, the scattered light will be of short wavelength and the colour of this haze layer is blue in colour.
“Pluto is a mysterious object that is constantly surprising us, There had been hints in earlier remote observations that there might be haze, but there wasn’t strong evidence to confirm it really existed until the data came from SOFIA. Now we’re questioning if Pluto’s atmosphere is going to collapse in the coming years – it may be more resilient than we thought”
– Michael Person, MIT’s Wallace Astrophysical Observatory.
SOFIA did its observation by witnessing an auspicious moment. It chased the shadow formed on earth when Pluto passed in front of a distant star. This rare occultation helped them to look at the backlit by that star on June 29, 2015, and this gave SOFIA a clear visual of the atmosphere of this planet. This video will give you a clear vision of that flying mission to know how auspicious that moment was.
A few months back, I heard a news report about a comment made by NASA Chief, which tells us that Pluto is a planet.
To be frank, me too want Pluto back as our 9th Planet. It did hurt when IAU downgraded it. Not fair for a guy with heart on his surface. Maybe we should wait, to hear, “Pluto retrieved its titles of Planet”.
-Arun S
Image Credits: NASA
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