It is the closest a comet has flown to the Earth since July 1770, when Lexell’s Comet passed at 1.4 million miles, so close that astronomer Charles Messier recorded that it coma looked four times the size of the full Moon.
Captain Cook, sailing in the South Pacific, saw the comet for the first time shortly before dawn on August 30 and measured its tail at 42°.
However, Pan-STARRS is unlikely to put on such a spectacular display. Its course means that although it is close to our planet, it is far away from the Sun, making it look very dim, although it may produce some meteors in the 48 hours leading up to its closest approach.
It is the first time the comet has ever been spotted and some astronomers have speculated that it may be a piece of comet 252P/LINEAR 12 which has broken off.
Comets are different to asteroids as they are made up of gas and ice rather than rock or metal. It is thought they could have seeded Earth with the building blocks of life, brining huge amounts of chemicals and water.
252P/LINEAR 12 will pass at a distance of 3.2 million miles on March 21 – about the same distance as Halley’s Comet, and around 14 times the distances between the Earth and the Moon.
“Both are visible from the UK, but are very faint," said Dr Robert Massey of the Royal Astronomical Association.
“252P/Linear 12 will need very large binoculars or realistically a decent telescope, and P/2016 BA14 will be even fainter.
“Given that it`s in the sky at the same time as the Moon, I think this will be a struggle for anyone but advanced amateur astronomers and obviously professionals.”
From London on March 22 the comet will appear above the horizon in the constellation Leo from around 1am then stay just North of the lion’s ‘head’ as the night progresses.
The PanSTARRS comet – named after the observatory in Hawaii that first spotted it – will the third-closest comet to pass the Earth since records began and is travelling at 31,345 miles per hour (50,445 km/h) through space. It will be the third-closest known comet to pass our planet in recorded history.
But even if it is difficult to see on Earth, professional stargazers are planning to use the Hubble Space Telescope to look at both comets in detail. Light given off by the comets acts like a fingerprint so scientists will be able to work out if the bodies were originally one.
Astronomer Michael Kelly from the University of Maryland said: “We have secured six orbits of Hubble Space Telescope time to snap some high-resolution photos during the close approach.”
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