Once-in-a-437-year chance: Newly discovered comet could be visible in night sky

A comet called Nishimura discovered just a month ago could be visible to the naked eye this weekend, offering stargazers a once-in-a-437-year chance to observe the celestial visitor.

The ball of rock and ice, whose exact size remains unknown, is named after the Japanese amateur astronomer Hideo Nishimura who first spotted it on Aug. 11.

It is rare that comets reach their moment of peak visibility so soon after being discovered, said Nicolas Biver, an astrophysicist at the Paris Observatory.

"Most are discovered months, even years before they pass closest to the sun," he told AFP.

The comet only swings by the sun every 437 years, he said, a long orbital period that sees it spend much of its time in the freezing outer solar system.

When comets approach the sun from the vastness of space, the heat causes its ice core to turn into dust and gas, which form a long tail.

The sun's light reflects off this tail, allowing us to view comets from Earth.

Nishimura, which has the scientific name C/2023 P1, will pass closest to the sun on Sept. 17. 

It will be 33 million kilometers (20 million miles) from the sun, which is less than a quarter of the distance between the Earth and the sun, Biver pointed out.

The comet will then pass harmlessly by Earth at a distance of 125 million kilometers.

For stargazers, the comet will be easiest to observe this Saturday and Sunday, particularly in the Northern Hemisphere.

"The best thing to do is look at the sky before sunrise, in a northeastern direction to the left of Venus, in a clear sky, free of pollution," Biver advised.

People with small binoculars will easily be able to enjoy the spectacle. But, if conditions allow, the comet may also be visible to the naked eye.

The comet's tail is greenish, because it contains "more gas than dust," Biver said. (AFP)