Fireworks planned if comet survives risky flyby of the sun

A comet is expected to risk having its tail cut off Friday by flying dangerously close to the sun, promising fireworks next month if it survives the challenging flypast.

Astronomers believe that comet Tsuchinshan-ATLAS has been hurtling headlong through the void of space toward the center of the solar system for millions of years.

Named after the Chinese observatory and South African program that detected and confirmed its existence in 2023, the ball of rock and ice may have formed at a distance up to 400,000 times that between Earth and the sun, the models suggest.

Until now, you had to be in the southern hemisphere to hope to see it with the naked eye.

But on Friday evening, it should get as close as possible to the sun, before returning to Earth.

From October 13, the comet will be visible in the northern hemisphere.

If the weather permits, “it will be obvious” every night “in the direction of the setting sun”, astronomer Lucie Maquet of the Paris Observatory explained to AFP.

“A bright comet”

But this prediction assumes that the comet does not fly too close to the sun.

When comets approach our star, the melting ice in their core releases a long trail of dust that reflects sunlight.

This characteristic tail is also a sign that the comet is outgassing. If the sun affects the comet too much, it risks disintegrating.

Because the pile of frozen water and rocks “might not resist the force of gravity from the sun,” a catastrophe “is always possible,” Maquet said.

The good news is that the comet, officially named “C/2023 A3” by scientists, appears to have a rather massive core.

There is therefore “a good chance that it will survive” its sunny passage, estimates the astronomer.

Initial predictions that the comet would be particularly bright during its visit to our sky have since been revised downwards.

“But it will definitely be a bright comet,” Maquet said.

An unpredictable future

The future trajectory of the comet is unpredictable.

His solar stay will not be without consequences on his journey, disrupted by the gravitational attraction of the celestial objects he passed through and by the weight loss inflicted by the violent rays of the sun.

According to models from the Institute of Celestial Mechanics at the Paris Observatory, it could be “ejected from the solar system and lost among the stars”.

It all depends on what encounters the comet encounters as it travels through the Oort Cloud – an icy belt of tiny objects thought to exist at the edge of the solar system up to 3.2 light years away – in a few thousand years.

It would be enough, according to Maquet, for the comet to pass next to an object “which deflects it sufficiently for a return to the solar system”.

© 2024 AFP