New Delhi: NASA's Hubble Space Telescope has confirmed the size of the largest icy comet nucleus ever seen by astronomers. The diameter of the nucleus is estimated to be approximately 80 miles across.


Hubble has confirmed that the nucleus is bigger than the US state of Rhode Island. The findings were recently published in The Astrophysical Journal Letters. .


All About The Comet Bernardinelli-Bernstein


The behemoth comet is called C/2014 UN271, or Bernardinelli-Bernstein. The nucleus of C/2014 UN271 is about 50 times larger than the nuclei of most comets. 


The mass of the nucleus is estimated to be 500 trillion tons, which is a hundred thousand times greater than the mass of a typical comet found much closer to the Sun. 


Bernardinelli-Bernstein is moving through the solar system at a speed of 22,000 miles per hour. 


The comet measures 15 times taller than Mount Everest, according to a study published in the journal Astronomy & Astrophysics.


Bernardinelli-Bernstein is almost unfathomably large and difficult to comprehend, and is six times larger than the comet that caused the extinction of dinosaurs about 65 million years ago.


The comet will not come within a billion miles of Earth. It is the prominent archetype of distant comets, whose activity is driven by hypervolatiles, which include compounds such as carbon monoxide and methane. 


Bernardinelli-Bernstein is almost twice as large as Hale-Bopp, which was an unusually bright comet that flew close to Earth in 1997. 


Bernardinelli-Bernstein is heading towards a perihelion of almost 11 astronomical units, or 1.62 billion kilometres, in 2031. Perihelion is the point nearest to the Sun in the path of an orbiting celestial body. 


Comet C/2002 VQ94 was the previous record holder. Discovered in 2002, it has a nucleus estimated to be 60 miles across.


Quoting David Jewitt, a co-author of the new study, a NASA statement said that comet Bernardinelli-Bernstein is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system. 


He said that researchers had always suspected the comet to be big because of its brightness at such a large distance, and now, they have confirmed this.


Findings Of The Study


Bernardinelli-Bernstein was discovered as part of the search for outer solar system objects with the Dark Energy Survey at Cerro Tololo Inter-American Observatory in Chile. Astronomers Pedro Bernardinelli and Gary Bernstein had discovered it in archival images from the Dark Energy Survey. The announcement of the comet was made on June 19, 2021. 


According to the study, Bernardinelli-Bernstein was first accidentally observed in November 2010. At that time, the comet was at a distance of three billion miles from the Sun. 


Man-To Hui, the lead author of the study, said this is an amazing object, given how active it is when it is still so far from the Sun. 


He said the astronomers guessed the comet might be pretty big, but they needed the best data to confirm this. Hence, the team used Hubble to take five pictures of Bernardinelli-Bernstein on January 8, 2022, the study said.


How Did Hubble Image The Nucleus?


However, a huge shell of dust and gas was enveloping the nucleus of the comet. Its current distance from Earth is too far for its nucleus to be visually resolved by Hubble. 


The telescope data showed a bright spike of light at the location of the nucleus. 


The researchers made a computer model of the dusty coma surrounding the nucleus. Then, they adjusted the coma to fit the Hubble images. 


After this, they subtracted the glow of the coma, as a result of which they were left with a starlike nucleus.


The Nucleus Is “Blacker Than Coal”


The researchers compared the brightness of the nucleus to earlier radio observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The combined data help them determine the diameter and the reflectivity of the nucleus.


According to the new Hubble measurements, the comet has a darker nucleus surface than previously thought.


Jewitt said the nucleus is big and "blacker than coal."


Where Is Bernardinelli-Bernstein Coming From?


Bernardinelli-Bernstein has been falling toward the Sun for over one million years, and is coming from the hypothesised nesting ground of trillions of comets, called the Oort Cloud, which lies far beyond Pluto, and the most distant edges of the Kuiper Belt. 


Oort Cloud is the predicted collection of icy objects farther away than everything else in the solar system, and is thought to have an inner edge at 2,000 to 5,000 times the distance between the Sun and the Earth. 


According to the study, Bernardinelli-Bernstein follows a three-million-year-long elliptical orbit. This takes it as far from the Sun as roughly half a light-year. 


It is currently less than two billion miles from the Sun, and is falling nearly perpendicular to the plane of our solar system. 


The temperatures at this distance are about minus 348 degrees Fahrenheit. However, this temperature is warm enough to cause the carbon monoxide on its surface to sublimate and produce the study coma.


Significance Of The Study


With the help of Bernardinelli-Bernstein, astronomers can get a clue about the size distribution of comets in the Oort Cloud. In this way, they can determine the total mass of the diffuse cloud. 


The study of comets is very important because they are deep-freeze samples of the composition of the early solar system, preserved for billions of years. Since they approach the Sun from all directions, the Oort Cloud must be spherical in shape.


In order to determine the Oort Cloud's role in the solar system's evolution, astronomers need more observational evidence.


As Bernardinelli-Bernstein approaches and passes perihelion, monitoring of dust and gas emission will allow astronomers to study the comet's activity pattern.