A 'rare celestial event' will be visible in the night sky on Friday as the alpha Monocertoid meteor shower is set to be at its most impressive since 1995.

The shower is the result of the Earth passing through the tail of a mysterious comet and will see meteors moving at 140,000 miles per hour. 

Also known as the 'Unicorn shower', the meteors will appear in the sky in the area of the Monoceros or Unicorn constellation - near Orion the Hunter.

If the show is as big as the 1995 shower it will be one to watch, say Esko Lyytinen and Peter Jenniskens, the meteor experts who predicted the bigger outburst.

If the sky is clear you will be able to witness the shower from about 4:50am GMT on the 22nd of November in South America, the eastern parts of North America, western Europe and west Africa.

There will be up to 400 shooting stars visible over the course of about an hour, or about seven per minute.

In contrast the recent Leonid meteor shower saw about 15 shooting stars fall through the sky per hour.

This is only a prediction and things could change. The comet has 'yet to be discovered' and so the team have used estimates of its path from previous showers to come to the suggestion of a major shower on Friday.

'I now think there is a pretty good chance there may be no outburst at all. And even if there is, it won’t be as impressive as many think', says NASA Meteoroid Environment Officer, Bill Cooke.

He says the fact we don't know the true orbit of the comet makes it difficult to predict whether we will pass through the centre of the comet tail's stream or miss it completely.

'If [the orbit] is much smaller, or larger, the distance from the stream center will be bigger, and there will not be any sky show, just the normal, puttering along with their normal rate of 3 or so meteors per hour. '

He said it was still worth astronomers venturing out to watch the shower as they could better predict the orbit of the comet for future showers by counting how many meteors burn up over the course of an hour.

Previous large Unicorn showers happened in 1925, 1935, 1985 and most recently 1995, although all but the 1995 shower were unexpected.

The 1995 shower was the first time a large outburst had been predicted in advance.

Mr Lyytinen says conditions are shaping up to be similar to those surrounding the 1995 shower and the moon is waning so its light shouldn't dampen the show.

Unlike most meteor showers that can go on for several hours the Unicorn outburst is often over within an hour, according to the American Meteor Society.

They recommend finding an area with as little light pollution as possible and arriving an hour before the shower is due to start just in case the predicted start time isn't exactly right.