Comet weighing 500,000 billion tons rushes towards Earth

The Hubble Space Telescope photographed the largest comet ever recorded, helping astronomers calculate its enormous size.

The comet's nucleus, an ice structure excluding the tail, is 129km in diameter and weighs about 500,000 billion tons. This cold comet is called C/2014 UN271 or Bernardinelli-Bernstein. The object was discovered in 2010 by two astronomers Pedro Bernardinelli and Gary Bernstein. However, it was not until recently that researchers were able to determine its size. This is partly because the comet is about 3.2 billion km from Earth, farther than Uranus, and partly because it is covered by a gas and dust shell that forms the characteristic tail trail.

C/2014 UN271 is the largest comet with a nucleus ever discovered.

By combining computer modeling with Hubble space telescope observations, a team of astronomers led by Man-To Hui of Macau University of Science and Technology was able to isolate the comet's core from shell, revealing the size of its main body. "The comet is very massive and blacker than coal," said study co-author David Jewitt, published April 12 in The Astrophysical Letters. "We always assumed this comet must be very large because it was so bright at such a distance. Now we can confirm the hypothesis."

C/2014 UN271 is slowly moving towards the Sun but not endangering the Earth. In fact, astronomers predict it won't come any closer to our planet than Saturn in 2031. One day, the comet will fly away from the Sun and not begin its return journey. until it reaches about half a light-year. In total, C/2014 UN271 takes 3 million years to complete its orbit around the Sun.

Comets are large objects made of ice and dust, orbiting the Sun, famous for their long tail trails. Sometimes, their tail trails are clearly visible from Earth. In particular, distant comets attract much attention from astronomers because they are considered the most primitive vestiges of the early Solar System. For most of their existence, they are preserved in the low-temperature environment of the outer Solar System.

Although less affected by heat from the Sun, some comets work by releasing clouds of gas or other matter that increase their luminosity. Scientists are still not sure why. Comets like C/2014 UN271 provide an important opportunity for them to learn more about these distant ice objects.