Rare, green comet to be visible from Earth for the first time in 50,000 years – where and when you can see it

A comet that hasn’t swung by our part of the solar system since the last Ice Age will revisit for the first time in 50,000 years this Friday.

The last time the comet appeared, Homo sapiens and Neanderthals shared the planet and indigenous Australians had only just made the journey over the southeast Asian land bridges to this continent.

Friday the 13th in 2023 may not be as unlucky as we think.

The comet is named C/2022 E3 (ZTF) after the Zwicky Transient Facility, which first spotted it passing Jupiter in March last year. With a name like that, I am surprised they didn’t go with “WTF.”

Whether the name rolls off the tongue or not, C/2022 E3 (ZTF) will roll into the inner solar system coming to within around 160 million kilometres from the sun – marginally further from our central star than the Earth is from the sun.

From there it will move towards Earth, reaching as close as 42 million kilometres from the planet on 2 February, when it will be at its brightest. On its approach toward the sun, the comet will not be visible to the naked eye, but should be able to be seen through binoculars.

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Eventually, as it gets closer to the Earth, it may become visible to the naked eye.

NASA says that comet afficionados in the northern hemisphere should be able to observe C/2022 E3 (ZTF) with binoculars or small telescopes in January, but star-gazers fixing their instruments on the southern skies will have to wait till February.

In the Sky reports that New York City observers will be able to see C/2022 E3 (ZTF) as it rises at 11:18 p.m. EST (04:18 a.m. GMT) and reaching an altitude of 64° over the eastern horizon, before fading away around 6:07 a.m. EST (11:07 a.m. GMT).

The comet was discovered in March 2022 by the wide-field survey camera at the Zwicky Transient Facility. Initially believed to be an asteroid, it revealed itself as a comet when it emerged from Jupiter’s orbit and underwent a rapid “brightening”.

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C/2022 E3 (ZTF) has a distinct green colour and two tails, one of which is very long. Scientists suggest the comet head’s green colour is likely due to a dicarbon molecule (chemical compounds with two bonded carbon atoms). Long exposure photographs will show these features more clearly than observations with small telescopes or binoculars.

For anyone who wishes to see the comet, the Virtual Telescope Project will host a free livestream on 13 January, 3pm AEDT (12 January, 11pm EST). Watch the live webcast on the project’s website or YouTube channel.

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