Comet ATLAS may have had a brief moment in the Sun earlier this year when it became one of the brightest comets spotted in the last decade by sky gazers. However, the fragile comet broke under strain and disintegrated into smaller bits in April 2020.

However, scientists believe that ATLAS might be a blast from the past. A recent study provided information on the history of our planetary system and how it came to be, so its brief brush with our Solar System was not in vain.

 Comet Atlas: What Happened to Its Tail Now That It's No Longer Tailing Anything?
(Photo: Wikimedia Commons)
The NASA/ESA Hubble Space Telescope has provided astronomers with the sharpest view yet of the breakup of Comet C/2019 Y4 (ATLAS). The telescope resolved roughly 30 fragments of the comet on 20 April. The comet was first discovered in December 2019 by the ATLAS (Asteroid Terrestrial-impact Last Alert System), and its fragmentation was confirmed in April 2020. Credit: NASA, ESA, D. Jewitt (UCLA), Q. Ye (University of Maryland)

Comet Atlas: A Blast From the Past

In a NASA blog post, astronomer Quanzhi Ye of the University of Maryland in College Park that ATLAS is a broken-off fragment of that ancient visitor from 5,000 years ago. The researcher based the findings on NASA's Hubble Space Telescope studies. Why? Because ATLAS travels on the same orbital "railroad" as a comet that was discovered in 1844. This indicates that the two comets are likely siblings from a parent comet that split away ages ago. Maik Meyer, an amateur astronomer, was the first to notice the connection between the two comets.

Families of comets like this are relatively frequent. The most spectacular visible example occurred in 1994 when Jupiter's gravitational force dragged the doomed comet Shoemaker-Levy 9 (SL9) into a string of fragments. This "comet train" only lasted a few days. In July 1994, it began to fall towards Jupiter in pieces.

However, comet ATLAS is "strange," according to Ye, who saw it with Hubble at the moment of the breakup. Unlike its presumed parent comet, ATLAS was destroyed while orbiting the Sun at a distance of more than 100 million miles. This was a significant distance from where its father had crossed the Sun. It highlights its uniqueness, Ye explained.

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Still, Ye wondered how this comet survived its last orbit around the Sun 5,000 years ago if it split apart like that. The researcher said it is the first time a long-period comet family member has been spotted splitting up before going closer to the Sun. Ye added it is quite uncommon since scientists wouldn't anticipate it.

Comet Atlas Broke Apart One Fragment Into Another

Observing how the pieces split apart can reveal information on how the parental comet was built and formed. Comets are thought to be fragile clumps of dust and ice, according to popular belief. They may also be lumpy, similar to raisin pudding.

After a year of research, Ye and co-investigators say that one fragment of ATLAS dissolved in a matter of days. At the same time, another persisted for weeks. This indicates that one portion of the nucleus was more powerful than the other," he explained.

One theory is that released material streamers whirled up the comet so quickly that centrifugal forces ripped it apart. Another theory is that it contains so-called super-volatile ices, which blasted the chunk apart like an explosive aerial fireworks display. It's complex because we see these hierarchies and the progression of comet fragmentation, he said. He added that Comet ATLAS' behavior is intriguing but difficult to explain.

The surviving sibling of Comet ATLAS will not return until the 50th century.

Researchers reported their study, titled "Disintegration of Long-period Comet C/2019 Y4 (ATLAS). I. Hubble Space Telescope Observations," in the Astronomical Journal.

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