Comet ATLAS: This Cosmic Flop Might Have Been a Spectacular Sight to Civilizations

A comet that piqued scientists' interest when it first appeared in our sky at the end of 2019 but shattered months later into 30 tiny ice shards.

Studies performed while the Comet ATLAS was still intact have revealed information about the comet's "family," which dates back thousands of years.

On December 28, 2019, the University of Hawaii's Asteroid Terrestrial-impact Last Alert System, or ATLAS, spotted comet ATLAS for the first time.

Quanzhi Ye, University of Maryland's astronomer, used the Hubble Space Telescope to examine the comet. Using their data, Ye and his colleagues deduced that comet ATLAS was a relic of a comet that likely raced past our sky 5,000 years ago.

This old comet passed within 23 million miles of the sun, closer to Mercury to our star. NASA said Stone Age civilizations in North Africa and Eurasia most certainly saw it.

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

Weird Comet ATLAS Broke Apart

Although there are no records of this observation, researching comets in the way that Ye and his colleagues did with comet ATLAS aids in tracing comet beginnings. In fact, ATLAS' trajectory around the sun matched that of a comet discovered in 1844, implying that the two comets were "siblings" from a parent comet that had broken apart decades earlier.

Space.com said Maik Meyer, an amateur astronomer, was the first to connect comet ATLAS with the comet in 1844.

It's not unusual for a comet to split into "families." When the comet Shoemaker-Levy 9 was destroyed by Jupiter's gravitational pull in July 1994, which Space.com also reported, Hubble and Galileo spacecraft were focused on the gas giant. It created a "comet train" consisting of comet fragments that formed a line.

However, Ye said ATLAS acted "weirdly." He said he couldn't figure out why ATLAS broke down while crossing the sun much closer than its parent comet.

Even yet, Ye was perplexed as to how this comet withstood its last orbital path 5,000 years ago if it had torn apart so badly. According to the researcher, this is the first time a long-period comet close relative has been seen splitting off before approaching the sun. It's highly unusual, according to Ye, because scientists wouldn't expect it.

Comet ATLAS Had Different Components

The pieces imply that various portions of ATLAS had varied architectures or components, significantly because one comet fragment disintegrated in days while another survived for weeks, Space.com said. This indicates that one element of the nucleus was more powerful than the other, Ye explained.

The authors have a few ideas about why the pieces had varied lifespans, which might be connected to the old parent comet's unknown makeup. According to NASA, one idea is that "streamers of expelled debris" tore the comet apart due to centrifugal forces. Alternatively, volatile ices might have blown apart the weaker component like "an exploding aerial structure," according to the agency.

While ATLAS is no longer visible, its sister should be seen from Earth at some point in the future - but only in the far future. The best prediction among astronomers is that it will pass past our planet in the 50th century.

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