A comet that has not been seen since the first A wise man roamed the Earth is streaking across the sky and humans have a unique opportunity to see it this week.
Comet C/2022 E3 (ZTF), also known as the “green comet”, will pass as close as possible to our planet this Wednesday. Like other comets with long orbital periods, it doesn’t pass by very often.
In fact, the “green comet” last visited the inner Solar System 50,000 years ago, around the time Stone Age humans are believed to have begun to develop language.
And due to the nature of its orbit, it may never visit the inner Solar System again, meaning this could be humanity’s last chance to view comet C/2022 E3 (ZTF).
What do we know about comet C/2022 E3 (ZTF) and why is it green?
The comet was discovered in March 2022 by astronomers conducting a wide-field astronomical survey at the Zwicky Transient Facility in California, United States.
Since then it has increased considerably in brightness and can be seen in the sky from the northern hemisphere in the early morning.
Its closest approach to the Sun, known as perihelion, occurred on January 12, while its perigee (its closest pass to Earth) will occur on Wednesday, February 1.
As it approaches the Sun, it grows brighter as radiation from the star heats it up and creates a green coma, the hazy gas envelope of heated materials such as water, carbon dioxide and carbon monoxide.
It also has a short, broad dust tail, and a longer, fainter ion tail, created when the solar wind interacts with the comet’s coma.
The green glow is the result of ultraviolet radiation from the Sun illuminating gases emitted from the comet’s surface.
C/2022 E3 (ZTF) is believed to originate from the Oort Cloud, a region of the outer solar system that contains billions of comets in stable orbit around the Sun.
How to spot the “green comet”
Currently it can be seen in the night sky of the Northern Hemisphere with a telescope or binoculars.
However, as it gets closer, it is already visible to the naked eye in very dark skies, according to the Royal Greenwich Observatory (London).
When it approaches Earth on Wednesday, the comet will be about 42 million km from our planet, and will also be visible from the Southern Hemisphere.
But NASA warns that comets — and their visibility — are notoriously unpredictable.
To find out where in the sky the comet will appear, you can use a stargazing app.
It is expected to appear near the constellation Camelopardalis on Wednesday, surrounded by the Big Dipper, the Big Dipper and the Little Dipper.
To avoid disappointment when trying to see it in the night sky, make sure it’s not going to be too cloudy, that you have a view of the right part of the sky from your vantage point, and bundle up well before you head out, the observatory said.
He adds that you have to let your eyes adjust to the dark for at least 15 minutes and avoid looking at your mobile or other light devices so that your eyes remain sufficiently sensitive in the dark.