What is a “green comet” and how do you see it? | comets

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A strange comet is causing excitement this week. Take a look at what we know about the unusual celestial body, and how best to get a glimpse of it.

Why is this comet special?

This particular comet is called C/2022 E3 (ZTF) and was discovered by astronomers in March 2022 at the Zwicky Transit Facility in California. Dubbed the “green comet” because of its green glow, it is believed to have come from the Oort Cloud – a group of icy bodies thought to reside in the outermost part of the solar system.

While some comets are relatively frequent visitors – Halley’s Comet appears every 76 years on average – C/2022 E3 (ZTF) orbits the Sun every 50,000 years. In other words, the last time it could be seen from Earth was in the Stone Age, when not only modern man, but also Neanderthals turned their gaze towards the stars.

Why is it green?

The green glow is not unique to this comet, although it is an interesting feature. This phenomenon is thought to arise from an interaction between sunlight and diatomic carbon. Diatomic carbon is an unstable gaseous form of the element in which carbon atoms are bonded together in pairs. Scientists say it forms on top of a comet when large carbon-based materials are broken up by sunlight as the comet approaches the sun.

When diatomic carbon is excited by ultraviolet light, it emits light, producing the green coma seen surrounding the comet’s nucleus. However, ultraviolet light can also cause diatomic carbon to decompose. Experts say this explains why the comet’s tail does not appear green.

Can I see a comet without a telescope?

Not all comets are visible to the naked eye, and it is often difficult to predict how bright a comet will be. But reports indicate that C / 2022 E3 (ZTF) has already been spotted by some observers without equipment once the moon sets, and it is hoped that it will remain visible to stargazers when it approaches its closest point to Earth on Wednesday and Thursday, when the point will be 0.28 AU. (26 million miles) from our planet.

However, you will get a better view if you can get your hands on binoculars or a telescope.

Where should I look?

Your best bet is to head out on a Wednesday night somewhere really dark — away from the bright lights of the city at night — and look for a smudge in the sky.

“Located in the north of our sky, the comet is currently close to Polaris, the pole star heading directly to the north,” said Jake Foster, Royal Observatory astronomer. The comet is best viewed after midnight, when it reaches its highest point in the sky. It will move a great distance across the sky from night to night as it makes its way towards the constellation Taurus over the coming weeks.”

Foster added that there are several free stargazing apps that can locate the comet to make the task easier.

“Using binoculars or a small telescope, you should be able to identify the comet as a faint green dot,” he added. “You’re lucky your sky is particularly dark, and you might even be able to see their broad tails, too.”

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