A RARE GREEN comet, that has not been seen for 50,000 years, is about to make its closest pass by Earth, becoming visible in a once-in-a-lifetime opportunity.

Called C/2022 E3 (ZTF), this celestial object hails from the Oort cloud at the outermost edge of the solar system.

Its green glow is a result of ultraviolet radiation from the sun lighting up the gases surrounding the comet’s surface.

The icy ball orbits the sun once every 50,000 years, which means the last time it went past the planet was during the Stone Age – when Neanderthals roamed the Earth.

It is due to pass closest to the planet – still some 42 million kilometres away – tonight, into the early hours of Thursday and in a very dark sky will appear as a faint smudge to those looking for it with the naked eye.

However, even if the moon is too bright for stargazers to spot the comet on tonight, they might be able to catch a glimpse of it a week later when it passes Mars.

Professor Don Pollacco, from the department of physics at the University of Warwick in England, told the PA news agency: “Comet C/2022 E3 passes closest to Earth tonight, on 1 February.

“It has been christened the “Green Comet” as pictures show the head of the Comet to have a striking colour.

“We understand this as due to light emitted from carbon molecules ejected from the nucleus due to the increase in heat etc during its closest approach to the sun, which happened around 12 January.

“Some comets approach the sun much closer and are completely evaporated by the intense radiation.”

He added: “As the comet approaches Earth (it’s still 42 million km away, so no chance of a collision) it appears to move more quickly across the sky on a night-by-night basis.

“Tonight the comet is about halfway between the pole star and the bright star Capella, overhead about 11pm.

“However, the waxing moon will make the Comet much harder to spot. To see it you’ll need a clear sky, binoculars and a bit of luck.

“Alternately, if you wait a few days to around 10 February, the moon will be less bright and the comet will be clearer to see in the southern part of the sky, passing Mars.”

Founder of Astronomy Ireland, David Moore, told The Journal last month that ZTF will likely be one of the brightest comets of the last few years,” he said.

“We’re polluting the oceans with plastic, the atmosphere with carbon dioxide and methane but also the nice dark night’s sky with artificial light that blocks out stars and comets.”

People in cities and large towns will struggle to get a view of the comet even when it gets its closest to Earth, he said.

“Get away from streetlights,” Moore advised.

“That’s the best thing you can do to increase your odds of a good view. We are lucky because the comet will be near the North Star. It will be visible from dusk to dawn so you don’t have to perfectly time you viewing. Ireland has a ringside seat.”

With reporting from Jamie McCarron