Before its 80,000-year absence, a study predicts the “fate” of a comet visiting us this fall

Previous reports indicated that Comet Tsuchinshan-ATLAS (C/2023 A3) will pass close to our planet and will be visible to the naked eye next October.

A report issued last May said that the comet is getting brighter and its tail is growing to become as bright as the planet Venus (the brightest object in Earth's sky), making it visible to the naked eye.

But a new study published this week tells a very different story. In a paper published July 9, scientists predict the comet's "imminent collapse" before it reaches perihelion, its closest point to our star, on September 27.

The comet comes from the Oort Cloud, a region surrounding our solar system that is home to millions of comets.

Astronomers discovered the comet in February 2023 in a joint effort between the Asteroid Terrestrial Impact Last Alert System (ATLAS) telescope in South Africa and China's Zuochenshan Observatory.

C/2023 A3 enters the inner solar system, orbiting the sun once every 80,000 years. Hopes were high that the comet would become bright enough to be seen with the naked eye by the fall of 2024 because it will come so close to the sun that its tail of ice and dust will reflect light back to Earth, making it appear brighter.

Astronomers call this forward scattering.

Comet C/2023 A3's close perihelion may be the reason for its expected high brightness, but its proximity to the Sun also puts it at risk of collapse.

"The comet is expected to disintegrate before reaching perihelion. Independent evidence points to its imminent inevitable collapse," said the paper, written by Czech-American astronomer Zdenek Sikanina.

This evidence includes that the comet was not bright enough before perihelion as most similar comets from the Oort Cloud are. According to the paper, the comet's nucleus, a solid core of rock, dust and frozen gas, also appears fragmented, and its distinctive tail is unusually narrow.

"This evidence suggests that the comet has entered an advanced stage of fragmentation," Sikanina wrote, adding that it is shedding "small, dark, porous, oddly shaped pieces."

"I expect the object to disappear and cease to exist as an active comet before perihelion," Sikaina explains, although the comet's fate has yet to be determined.