The Hubble space telescope has captured the clearest images yet of comet ATLAS and found it has shattered into dozens of pieces each at least the size of a house.
The comet was discovered by the ATLAS (Asteroid Terrestrial-impact Last Alert System) robotic astronomical survey system in Hawaii in December 2019.
It became incredibly bright up until mid-March, with astronomers speculating it could be one of the brightest comets in decades – but it wasn’t to be.
It started to get dimmer very quickly, leading astronomers to speculate that its icy core was breaking apart into many different pieces.
ATLAS’s fragmentation was confirmed by amateur astronomer Jose de Queiroz, who photographed around three pieces of the comet on 11 April.
The Hubble Space Telescope has provided astronomers with the sharpest view yet of the breakup of Comet C/2019 Y4 (ATLAS). On the left is an image from April 20 showing 30 fragments and on the right is a April 23 image with another 25 pieces
This graphic shows an asteroid breaking apart. Over millions of years tiny rocks hit it causing it to spin, the spin is uneven and it causes the asteroid to split apart. A comet also breaks up from an uneven spin – but the spinning is caused by ice turning to gas and spouting from the core
There was a lot of speculation in March that this could become the ‘comet of a generation’ as it had become incredibly bright.
This was in part due to a growing gaseous envelope surrounding the comet that had ballooned in diameter to a staggering 447,387 miles by mid-March.
In contrast the Sun has a diameter of 865,370 miles, Jupiter’s diameter is 86,881 miles and the Earth is just 7,917 miles.
Soon after this ATLAS began to become much dimmer, with speculation mounting that it had broken apart.
The Hubble Space Telescope’s new observations of the comet’s breakup on April 20 and 23 reveal that the fragments are all enveloped in a sunlight-swept tail of dust.
These images provide further evidence that comet fragmentation is probably common and might even be the dominant mechanism by which comets die.
The comet, named C/2019 Y4 (ATLAS), is pictured (green dot) glimmering in space by Jamie Cooper in Lincolnshire
‘Their appearance changes substantially between the two days, so much so that it’s quite difficult to connect the dots,’ said David Jewitt of UCLA.
He is the leader of one of two teams who imaged the doomed comet with Hubble.
‘I don’t know whether this is because the individual pieces are flashing on and off as they reflect sunlight, acting like twinkling lights on a Christmas tree, or because different fragments appear on different days.’
This type of destructive event doesn’t happen very often, according to Quanzhi Ye from the University of Maryland, who led the other observation team.
‘Most comets that fragment are too dim to see. Events at such scale only happen once or twice a decade,’ Ye said.
Because comet fragmentation happens quickly and unpredictably, reliable observations are rare and so astronomers aren’t sure what causes it to happen.
One suggestion is that the original nucleus at the centre of the comet spins itself into pieces due to jets of gas from the changing ice as it approaches the Sun.
As this venting is likely not evenly dispersed across the comet, it enhances the breakup.
This stunning image of comet C/2019 Y4 ATLAS was taken by Michael Jäger on March 18, 2020 and shows its bright green hue
The green Atlas comet can be seen in the top left of this image captured from a remotely operated observatory in New Mexico on March 18. At lower right are M81 and M82, well-known as large, gravitationally interacting galaxies
‘Further analysis of the Hubble data might be able to show whether or not this mechanism is responsible,’ said Jewitt. ‘Regardless, it’s quite special to get a look with Hubble at this dying comet.’
Hubble’s crisp images may yield new clues to the breakup. The telescope has distinguished pieces as small as the size of a house.
Before the breakup, the entire nucleus may have been no more than the length of two football fields.
The disintegrating ATLAS comet is currently located inside the orbit of Mars, at a distance of approximately 100 million miles from Earth when the latest Hubble observations were taken.
The comet will make its closest approach to Earth on May 23 at a distance of approximately 71 million miles.
Eight days later it will skirt to within just 22 million miles of the Sun.
NASAs Hubble Space Telescope is still working and has made more than 1.3 million observations since its mission began in 1990
The Hubble telescope was launched on April 24, 1990, via the space shuttle Discovery from Kennedy Space Centre in Florida.
It is named after famed astronomer Edwin Hubble who was born in Missouri in 1889.
He is arguably most famous for discovering that the universe is expanding and the rate at which is does so – now coined the Hubble constant.
The Hubble telescope is named after famed astronomer Edwin Hubble who was born in Missouri in 1889 (pictured)
Hubble has made more than 1.3 million observations since its mission began in 1990 and helped publish more than 15,000 scientific papers.
It orbits Earth at a speed of about 17,000mph (27,300kph) in low Earth orbit at about 340 miles in altitude.
Hubble has the pointing accuracy of .007 arc seconds, which is like being able to shine a laser beam focused on Franklin D. Roosevelt’s head on a dime roughly 200 miles (320km) away.
The Hubble telescope is named after Edwin Hubble who was responsible for coming up with the Hubble constant and is one of the greatest astronomers of all-time
Hubble’s primary mirror is 2.4 meters (7 feet, 10.5 inches) across and in total is 13.3 meters (43.5 feet) long – the length of a large school bus.
Hubble’s launch and deployment in April 1990 marked the most significant advance in astronomy since Galileo’s telescope.
Thanks to five servicing missions and more than 25 years of operation, our view of the universe and our place within it has never been the same.