12P/Pons-Brooks is a Halley-type comet larger than Mount Everest and appears every 71,3 years. The comet is expected to become visible to the naked eye in the coming weeks as it approaches the sun on April 21. The Guardian he says:
While some reports say 12P/Pons-Brooks was spotted as early as the 14th century, it was named after the French astronomer Jean-Louis Pons who discovered it in 1812 and the British-American astronomer William Robert Brooks who observed it later . It appears to have been in orbit since 1883. It is thought to have a nucleus about 30 kilometers in diameter, and is classified as a cryovolcanic comet, meaning it explodes with dust, gas and ice when pressure builds up inside it as it heats up. One such outburst last year caused it to brighten a hundredfold and gave it the name "devil's comet" since the nebula surrounding it was horn-shaped.
While the comet – and its green hue – has already been spotted in the night sky, experts say it's expected to get even brighter in the coming weeks.
"The comet is expected to reach magnitude 4,5 which means it should be visible from a dark location in the UK," said Dr Paul Strom, an astrophysicist at the University of Warwick.
“The comet is moving from the constellation of Andromeda to Pisces. As it does so it passes bright stars that will make it easier to spot on specific dates. In particular, on March 31st 12P/Pons-Brooks will be just 0,5 degrees from the bright star called Hamal,” he said.
Dr Robert Massey, deputy executive director of the Royal Astronomical Society on the other hand, said that even if the comet brightens, it will be difficult to see, adding that basic instruments such as small telescopes would help a lot.
"If you have a decent pair of binoculars, definitely try to look for it with them," Massey said, adding that apps that map the sky are also useful.
The best views of the comet will be when it is in the northern hemisphere. Massey said that those who want to see him should go outside on a clear afternoon and look low to the west-northwest as twilight falls.
"It would be good to avoid fog, moonlight, and light pollution in general."
