Hubble sees fragile comet break into dozens of pieces

April 29, 2020
Washington: NASA’s Hubble Space Telescope has seen a fragile comet, C/2019 Y4 (ATLAS), disintegrate into more than two dozen pieces.

Hubble identified about 30 fragments on April 20, and 25 pieces on April 23, NASA said on Tuesday, adding that all the pieces are enveloped in a sunlight-swept tail of cometary dust.

“Their appearance changes substantially between the two days, so much so that it’s quite difficult to connect the dots,” said David Jewitt, Professor at University of California, Los Angeles, and leader of one of two teams that photographed 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.”

The results are evidence that comet fragmentation is actually fairly common, said researchers.

It might even be the dominant mechanism by which the solid, icy nuclei of comets die. Because this happens quickly and unpredictably, astronomers remain largely uncertain about the cause of fragmentation.

“This is really exciting — both because such events are super cool to watch and because they do not happen very often. Most comets that fragment are too dim to see. Events at such scale only happen once or twice a decade,” said the leader of a second Hubble observing team, Quanzhi Ye, of the University of Maryland, College Park.

The comet was discovered on December 29, 2019, by the ATLAS (Asteroid Terrestrial-impact Last Alert System) robotic astronomical survey system based in Hawaii.

This NASA-supported survey project for Planetary Defense operates two autonomous telescopes that look for Earth-approaching comets and asteroids.

The comet brightened quickly until mid-March, and some astronomers anticipated that it might be visible to the naked eye in May to become one of the most spectacular comets seen in the last 20 years.

However, the comet abruptly started to get dimmer instead of brighter.

The disintegrating comet was approximately 146 million kilometres from Earth when the latest Hubble observations were taken.

If any of it survives, the comet will make its closest approach to Earth on May 23 at a distance of about 116 million kilometres, and eight days later it will skirt past the Sun at 40 million kilometres, NASA said. IANS