'Once-in-a-lifetime' green comet passes by Earth for first time in 50,000 years

  • The Jersey Astronomy Club captured the comet, named "C/2022 E3 (ZTF)" as it passed over the island last night (6 February).

Budding astronomers across the British Isles have managed to catch a glimpse of a "once in a lifetime" green comet in the sky this week.

The C/2022 E3 (ZTF) comet is the first of its kind to pass within 2,500 miles of Earth since the last Ice Age.

Another one is not expected for at least the next 50,000 years when it restarts its orbit around the sun.

Comets are a combination of frozen gases, dust and rock. 

As this one moved closer to the sun, it released gases which produced a green glow.

The comet was visible in the sky above Grosnez Castle in Jersey. The Cigar Galaxy can also be seen around 12 million light years away Credit: David Conboy

Its green glow is a result of ultraviolet radiation from the sun lighting up the gases surrounding the comet’s surface.

The icy ball orbits the sun once every 50,000 years, which means the last time it went past the planet was during the Stone Age – when Neanderthals roamed the Earth.

Professor Don Pollacco, from the department of physics at the University of Warwick, said: “Comet C/2022 E3... has been christened the “Green Comet” as pictures show the head of the Comet to have a striking colour.

“We understand this as due to light emitted from carbon molecules ejected from the nucleus due to the increase in heat etc during its closest approach to the sun, which happened around 12 January.

“Some comets approach the sun much closer and are completely evaporated by the intense radiation.”

He added that as the comet is still 42 million kilometres away from earth, there is no chance of a collision with Earth.

The comet will remain visible in the sky each night until around Friday 10 February.

Professor Pollacco said: "The moon will be less bright and the comet will be clearer to see in the southern part of the sky, passing Mars.”

The Greenwich Royal Observatory says that from the northern hemisphere, the comet is already visible in the night sky using a telescope or some binoculars.

It adds: "It’s worth noting, however, that comets can be unpredictable, and it’s hard to say with accuracy how bright the comet will be or what it will look like ahead of time.

"The comet looks like a fuzzy green ball or smudge in the sky. This green glow is a result of UV radiation from the sun lighting up the gases streaming off of the comet’s surface."

Advising on where the comet can be seen in the night sky, the Observatory said: “When it passes near Earth in February, the green comet will be in the constellation of Camelopardalis.

“After its closest approach, the green comet will move through Auriga and end up in Taurus mid-February.

“The comet will dim over the month as it moves away from us, and the time that it will be up in the sky during the night will get shorter and shorter.”

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