The largest comet would have been active at a record distance from the Sun

Astronomers from theUniversity of Maryland studied the case of comet Bernardinelli-Bernstein (BB), currently known as the biggest of all. According to scientists, BB would have been active long before the date of its discovery. An active comet is a comet whose ice vaporizes to form a coating of dust and vapor called “Coma”. For researchers, knowing when the comet becomes active is important. This information makes it possible to deduce the composition of the celestial body ice.


Comets are clusters of dust and ice. They become active according to temperature, which depends on its distance compared to the sun, and of the composition of its ice cream. Thus, the heat required to make it active determines the type of ice it contains.

At the end of their study, the researchers were able to determine the ice component which constitutes comet Bernardinelli-Bernstein. They published the results of their research in The Planetary Science Journal the 29th November 2021.

The largest and furthest comet from the Sun

Scientists have detected comet BB in June 2021. Its discovery was made possible thanks to Dark Energy Survey (FROM). Comet measures 100 km in diameter and it is located further from the sun than the planet Uranus. Although DES was able to photograph the luminous nucleus of the comet, the resolution offered few details.

Assoon as Tony farnham heard the existence of comet BB, he immediately thought of the Transient Exoplanet Survey Satellite (TESS). Tony Farnham is the lead author of the study. The point is, TESS observes each segment of the sky for 28 days. He therefore requested access to the potential images of BB that the spacecraft could have captured.

Comet Bernardinelli-Bernstein was active long before it was sighted

In fact, TESS recorded thousands of images of comet Bernardinelli-Bernstein between 2018 and 2020. In superimposing them, Farnham and his team were able to improve contrast and get a better rendering.

Following this arduous task, scientists were able to see a hazy glow around BB. They concluded that it is the coma of the comet that would be active. To be sure that the coma was not the effect of the stacking of images, they applied the technique to inactive objects in the Kuiper belt. The result allowed to conclude that the comet was indeed active.

The analysis of all the data allowed the astronomers to deduce that the ice of the comet is mostly carbon monoxide. It is a type of ice that begins to vaporize when it is five times farther from the sun than was BB at the time of its discovery. Therefore, the comet might have been active long before its observation.

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