The space telescope provided a clear view of the moment when the object shattered as it traveled through space.
The Hubble Space Telescope provided a clear view of the moment when comet C/2019 Y4 (ATLAS) shattered while traveling through space in recent weeks. According to astronomers, Hubble detected the presence of 30 fragments of the comet on April 20, and another 25 pieces three days later.
The comet was discovered in December 2019 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) located in Hawaii, United States. Because of its brightness, experts speculated that the object may be visible to the naked eye in May this year.
However, as it traveled through space, C/2019 Y4 started to abruptly dim, leading astronomers to believe that its ice core (common in all comets) could be fragmenting. It was thanks to Hubble’s observations that the team was able to verify that their hypothesis was correct: the comet was in fact disintegrating.
“Their appearance changes substantially between the two days, so much so that it’s quite difficult to connect the dots,” said David Jewitt, leader of one of the teams that photographed the comet, in a statement. “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.”
Because the comet’s fragmentation occurred very quickly, astronomers are still unsure of what caused it. According to Jewitt, one hypothesis is that the original core disintegrated due to the steam jets that leave the object when the ice evaporates. “Further analysis of the Hubble data might be able to show whether or not this mechanism is responsible,” pondered Jewitt. “Regardless, it’s quite special to get a look with Hubble at this dying comet.”
The comet was in orbit around Mars, at a distance of approximately 145 million kilometers (90 million miles) from Earth, when Hubble’s last observations were made. Astronomers estimate that it will come closer to our planet on May 23, at a distance of 115 million kilometers (71 million miles).