Once in 50,000-year comet to be visible from Earth | Space News

The comet is made of ice and dust and emits a greenish aura, and is estimated to have a diameter of about a kilometre.

A comet that will shoot past Earth and the Sun in the coming weeks for the first time in 50,000 years could be visible to the naked eye.

The comet is expected to pass nearest to Earth on February 1 and will be easy to spot with a good pair of binoculars or even with the naked eye, provided the sky is not too illuminated by city lights or the Moon.

As a fuller Moon could make spotting it difficult, the new Moon during the weekend of January 21-22 offers a good chance for stargazers, Nicolas Biver, an astrophysicist at the Paris Observatory, told the AFP news agency.

The comet was called C/2022 E3 (ZTF) after the California-based Zwicky Transient Facility, which first spotted it passing Jupiter in March last year.

Biver said the comet is made of ice and dust, and emits a greenish aura.

It is estimated to have a diameter of about a kilometre. That makes it significantly smaller than NEOWISE, the last comet visible with an unaided eye, which passed Earth in March 2020, and Hale-Bopp, which swept by in 1997 with a diameter of about 60 kilometres (37 miles).

But the latest visit will come closer to Earth, which “may make up for the fact that it is not very big”, Biver said.

“We could also get a nice surprise and the object could be twice as bright as expected,” he added.

The comet is believed to have come from the Oort Cloud, a theorised vast sphere surrounding the solar system that is home to mysterious icy objects.

The last time the comet passed Earth was during the Upper Paleolithic period, when Neanderthals still roamed Earth.

Biver said there was a possibility that after this visit the comet will be “permanently ejected from the solar system”.

Among those closely watching will be the James Webb Space Telescope. However, it will not take images, instead studying the comet’s composition, the astrophysicist said.

Thomas Prince, a physics professor at the California Institute of Technology who works at the Zwicky Transient Facility, told AFP that the comet’s proximity to the Earth made it easier for telescopes to measure its composition “as the Sun boils off its outer layers”.

This “rare visitor” will give “us information about the inhabitants of our solar system well beyond the most distant planets”, he added.

Prince said another opportunity to locate the comet in the sky will come on February 10, when it passes close to Mars.