Comet lighting the sky for the first time in 500 years

A rare comet travelling through space at 240,000 miles per hour is visible to the naked eye, according to a University of Hull astronomer.

Comet Nishimura, which was discovered in August, will be closest to Earth just before dawn on Tuesday, September 12 – giving the best opportunity to see it.

Professor Brad Gibson, Director of the E.A. Milne Centre for Astrophysics at the University of Hull, said that the comet is already visible to the naked eye around the hour after sunset and the hour before dawn.

He said: “The comet takes 500 years to orbit the solar system, Earth takes one year, and the outer planets can take many decades. Halley’s comet, which caused much interest during its last nearby visit to Earth in 1986, takes 76 years to orbit the solar system. So, to say this is a once in a lifetime opportunity to see Nishimura isn’t an exaggeration. It can already be seen but it will be 78 million miles from Earth on September 12 and that should be the best chance to see it with the naked eye. On average people have the chance to see such a naked eye comet once a decade – this is a rare and exciting opportunity.”

Comet C/2023 PI is named after Japanese astrophotography Hideo Nishimura who was taking long-exposure photographs of the sky with a digital camera on August 11.

Professor Gibson describes comets as ‘chunks of ice and rock’. As they pass ever closer to the Sun it heats the comet liberating an icy gas which give them their distinctive tail.

They are left over from the formation of solar system nearly 5 billion years ago and provide scientists like Professor Gibson with unique clues as to the earliest moments of planet and star formation in our local neighbourhood.

Tiny particles from comets are liberated by the Sun as a comet passes nearby. These particles of dust and rock continue on the same orbit as the comet itself and each year, Earth passes through this debris leading to spectacular meteor showers, some of which impact on the Earth, providing astrophysicists insights into planetary formation.

There is a debate between scientists over whether it was an asteroid or a comet which caused the extinction of dinosaurs 65 million years ago. That impactor was an estimated six miles wide.

According to Professor Gibson there is no danger of Nishimura colliding with Earth as astronomers have carefully charted its orbit and speed of travel.

He said: “What happened to the dinosaurs is a once in a 100-million-year event. People have been watching comets since ancient times with their interpretation then spanning everything from being portents of doom to simply being heralds of good news.”

Nishimura will pass closest to the Sun on September 17 – it will be 27 million miles from the Sun at that point, and there is a real chance it may not survive this close fly-by.

Scientists are still trying to estimate Nishimura’s size. Professor Gibson believes it could range from a few hundred meters to potentially a mile or two in diameter.

Understanding of the Comet is evolving, but it is thought that it could be responsible for an annual meteor shower named the Sigma-Hydrids, which takes place in December every year. Meteors in annual showers are often due to the Earth passing through cometary debris; the orbit of Comet Nishimura appears very similar to that of the Sigma-Hydrids debris, suggesting we have identified the origin of this annual meteor shower!

How to see Nishimura

The University of Hull’s E.A. Milne Centre for Astrophysics is equipped with the highest spec telescopes, but according to Professor Gibson says clear skies are all that is needed to see the comet.

A pair of binoculars, and skies not saturated by light pollution will further help people to see Nishimura. The angle of the Sun will preclude views and that is why it can only be viewed in the minutes around sunset and sunrise.

Look East - North East towards the crescent moon and Venus.