The Hubble space telescope has provided us with the sharpest views yet of the break up of comet C/2019 Y4 ATLAS. It has identified about 30 fragments on April 20, and 25 pieces on April 23.
The comet was discovered on Dec. 29, 2019, by the ATLAS (Asteroid Terrestrial-impact Last Alert System) robotic astronomical survey system based in Hawaii. It was seen to have 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. This led to astronomers speculating that the icy core may be fragmenting, or even disintegrating.
The fragments identified by the Hubble space telescope are all 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 of planetary science and astronomy at UCLA, 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”, he added.
Researchers say that the results are evidence that comet fragmentation is actually fairly common and It might even be the dominant mechanism by which the solid, icy nuclei of comets die. But because this happens quickly and unpredictably, astronomers remain largely uncertain about the cause of fragmentation.
The disintegrating comet was approximately 91 million miles (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 72 million miles (116 million kilometres), and eight days later it will skirt past the Sun at 25 million miles (40 million kilometres).
–Subo
Credits: NASA, ESA
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