There will be a ‘rare and exciting’ chance to see a comet with the naked eye over the next few days, believe astronomers, who have described the event as a ‘once in a lifetime’ opportunity.

Comet C/2023 PI - or Nishimura – is a newly discovered comet named after the Japanese astrophotographer Hideo Nishimura who spotted it when taking photographs of the sky with a digital camera back in August.

The comet is already visible to many sky gazers tracking its movement with telescopes, but for people living in the Northern Hemisphere, the best possible chance to see it with no help from technology will be as it reaches its closest point to Earth.

Nishimura is rocketing through space at an estimated 240,000 miles per hour.

The formation of a comet

Comets are a cluster of icy frozen gases, rocks and dust, which have been left over from the formation of the solar system about 4.6 billion years ago.

According to NASA, scientists sometimes refer to comets as ‘dirty snowballs’ or ‘snowy dirtballs’ depending on whether they contain more ice material or more rocky debris.

There are more than 3,500 known comets – but billions more are thought to be orbiting the sun beyond Neptune. Occasionally however, one moves into the inner solar system providing those on Earth with the chance of getting an excellent view.

Seeing Comet Nishimura

While the comet could prove to be visible for a number of days – as it comes towards and passes very close to Earth in its long journey – the optimum time for the best view is expected to be between Monday night and Tuesday morning.

With the hour after sunset on Monday and the hour before dawn on Tuesday offering the most favourable viewing windows.

Professor Brad Gibson, director of the E A Milne Centre for Astrophysics at the University of Hull, has described the event as a ‘once in a lifetime opportunity’ as comets often take hundreds of years to orbit the solar system.

He wrote on Twitter: “Get out there folks and hunt down Comet Nishimura over the next week ... you don't get many opportunities in your lifetime to catch a naked-eye one.”