Heart blacker than coal: astronomers saw the nucleus of the largest comet flying towards Earth

The Hubble Space Telescope has allowed astronomers to peer into the interior of comet Bernardinelli-Bernstein, aka C/2014 UN271, reports LiveScience. Its age is 4 billion years, and it is approaching our planet at a speed of 35,000 km/h. Fortunately, the comet does not pose a threat to us: in 2031, when it comes as close as possible, the distance between it and the Earth will be more than 1.5 billion kilometers. This is more than the average distance between Saturn and the Sun, and too far away for the comet to be visible to the naked eye.

Thanks to the Hubble Space Telescope, NASA astrophysicists have been able to identify the bright spot of light that hides the comet's heart, or nucleus, according to a study in the Astrophysical Journal Letters. After analyzing the data, scientists found that the Bernardinelli-Bernstein nucleus is 50 times larger than that of typical comets from the inner solar system. This is the largest nucleus ever observed. It was also possible to see the color of this ice core: according to the researchers, it is “blacker than coal”.

Previous studies have shown that the giant comet is 128 km across and that it is 100,000 times more massive than a normal comet. Because of its size, Bernardinelli-Bernstein was considered a dwarf planet until later observations showed it had a luminous tail. The comet last approached the Earth 3.5 million years ago, when it was at a distance of 2.6 billion kilometers from the Sun.