Comet Atlas Survived Close Call With The Sun, But Exploded Far Away From It

NASA’s Hubble Space Telescope has helped shed light on an interesting comet that flew past the Sun at a very close range some 5,000 years ago, survived the journey, but inexplicably disintegrated last year. Also known as ‘cosmic snowballs’ or ‘dirty snowballs,’ comets are said to be leftovers from a solar system’s formation and are predominantly made out of rock, ice, and dust. There are currently 3,743 comets that have been documented by space agencies, but scientists predict that there are billions of out there orbiting stars like the Sun.

For those wondering, comets aren’t capable of supporting life, unlike planets and possibly their moons too. They follow a strongly elliptical orbit on which they revolve around the sun, leaving behind a trail of dust and rocky material that forms its tail and can stretch millions of miles. Comets are known to float in the vastness of space for thousands of years, but when their orbit takes them close to the Sun, the star’s heat vaporizes its icy components and it risks total destruction. In some cases, a strong gravitational pull may cause a comet’s core to break apart. And that’s what makes the latest comet study more interesting.

Observed using the NASA-supported Asteroid Terrestrial-impact Last Alert System (ATLAS) robotic astronomical survey system, the comet ATLAS (C/2019 Y4) comet was first spotted in December of 2019. For the next few months after its discovery, it kept getting brighter. But surprisingly, it soon started to get dim and eventually disintegrated into more than a dozen pieces in April last year. This abrupt disintegration far away from the Sun was puzzling, as the comet survived a much closer encounter with the star some five millennia ago and came out in one piece. Unlike asteroids, comets aren’t often cited as a risk to collide with a planet and lead to a catastrophe.

Scientists who studied two fragments of the comet identified as C/2019 Y4-A and C/2019 Y4-B note that a spin-related disruption of its core may have caused it to break apart. But there’s also a possibility that rapid sublimation of sub-surface ice may have contributed to the disintegration. The latter would have looked akin to a giant firework explosion in space, somewhat like the stellar cosmic show produced by a meteor shower. As per astronomer Quanzhi Ye of the University of Maryland, ATLAS (C/2019 Y4) is part of an ancient comet that came within 23 million miles of the Sun, which is even closer than planet Mercury’s distance from the star.

That visit is said to have offered quite a cosmic show to Earth’s inhabitants during the stone age. But unlike the parent comet’s daring journey close to the Sun, ATLAS (C/2019 Y4) disintegrated at a much larger distance of roughly 100 million miles. This has left scientists puzzled as to how it survived its previous journey so close to the giant orb of hot gas at the center of the solar system some 5,000 years ago. So far, no theory has provided a full explanation of the weird history of this comet. The revived Hubble telescope captured the disintegration in action, but the space science community still has a lot of questions to answer.

Source: NASA


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