Comet predicted to light up Earth's skies this fall may be falling apart

A comet named C/2023 A3, also known as Tsuchinshan-ATLAS is said to potentially break apart before reaching its closest approach to Earth in October. However, if the comet survives until then, it may be visible to the naked eye.

A recent study suggests that the incoming comet, which could be visible without the aid of telescopes as it passes Earth later this year, might disintegrate before getting close enough for observation. Observations indicate that the comet is already showing signs of fragmentation, with the possibility of complete disintegration in the upcoming weeks or months. Nevertheless, experts hold contrasting opinions on this matter.

The cometary object was initially discovered by astronomers at the Purple Mountain Observatory in China on January 9, 2023, and then confirmed by NASA's Asteroid Terrestrial-impact Last Alert System (ATLAS) on February 22 of the same year. Its trajectory suggests that this could be its first-ever close approach to the sun and could eventually lead to its ejection from the solar system.

Expected to reach perihelion, the closest point to the sun, on September 27, C/2023 A3 may make its closest pass to Earth on October 13, at a distance of around 44 million miles (71 million kilometers). If the comet comes close enough to Earth, it will shine brightly, comparable to most stars visible in the night sky, allowing people to observe it using only their naked eyes for several weeks.

However, an astronomer named Zdenek Sekanina, who has been studying comets for over 50 years, presents an alternate perspective. In a study uploaded to the preprint server arXiv on July 8, Sekanina argues that C/2023 A3 might meet its demise before reaching perihelion.

According to Sekanina's paper, the comet has entered an advanced stage of fragmentation, as numerous dry, fractured refractory solids gather in dark, porous shapes. These fragments will gradually disperse in space, making them undetectable.

Historically, large comets tend to fragment at perihelion as the intense gravitational pull from the sun affects their icy composition. This was the case with comet ISON, which was violently torn apart during its solar flyby in 2014, as-reported by the European Space Agency.

Similar fragmentation was predicted for two comets that passed close to Earth recently: Comet Nishimura, which swung around the sun in September of last year, and Comet 12P/Pons Brooks (also known as the "devil comet"), which survived its solar journey in April of this year.

On the other hand, comets like C/2023 A3 can also undergo fragmentation while approaching the sun due to increased solar radiation leading to pressure on existing fractures. This was observed with comet C/2019 Y4, which fragmented spectacularly into numerous pieces before its close approach in 2020, as stated by NASA.

In the study, Sekanina proposes that various indications point towards the "inevitable collapse" of C/2023 A3. Firstly, the comet has not brightened as expected during its approach to the sun, suggesting a potential disruption in its nucleus or shell. Secondly, the comet's dusty tail appears thinner than anticipated with a peculiar orientation, further suggesting fragmentation. Finally, the comet seems to experience non-gravitational acceleration, potentially caused by jets of gas from within, pushing the nucleus apart.

However, not all scientists agree with Sekanina's observations. Nick James, an astronomer at the British Astronomical Association, who was not involved in the study, disagrees with the notion of impending fragmentation. He cautions against using the word "inevitable" in predictions about comets. However, James does mention that the study warrants careful observation of the comet.

As astronomers eagerly await the comet's arrival, time will unveil the ultimate fate of C/2023 A3. Whether it puts on a stunning display in Earth's skies or disintegrates into cosmic obscurity remains an intriguing question that nature alone can answer.