A green comet will soon be visible from Earth for the first time in 50,000 years

Depending on how bright C/2022 E3 (ZTF) becomes, it could even be visible to the naked eye.
Chris Young
Comet 2022 E3 (ZTF)
Comet 2022 E3 (ZTF)

NASA / Dan Bartlett 

Scientists recently discovered a green comet that was last visible in the night sky 50,000 years ago — that's so long ago that the Earth was in the midst of the Ice Age.

The comet was discovered on March 2, 2022, by astronomers using the Zwicky Transient Facility’s wide-field survey camera at the Palomar Observatory in San Diego County, California.

Now, a NASA blog post points out the fact that the comet will make its closest approach to the sun on January 12. It will be close enough to Earth that it may be visible to the naked eye.

A comet on a 50,000-year round trip

The comet, named C/2022 E3 (ZTF), has an incredibly long-period orbit that sees it pass through the outer reaches of the solar system when it makes its closest approach to the sun — which is why it takes such a long time to fly anywhere near Earth.

C/2022 E3 will stand out in the night sky compared to the surrounding stars due to its green hue as well as the dust tail streaking behind the icy space object.

The comet has a green hue due to its coma, which is an envelope that forms around space rocks as they approach a star. The heat generated by this coma causes the comet's ice to sublimate, or turn directly into gas.

Though it's not certain, there is a chance C/2022 E3 (ZTF) will be visible to the naked eye near the end of January. This depends on how bright the comet becomes as it approaches the sun. As NASA points out in its post, "the brightness of comets is notoriously unpredictable, but by then C/2022 E3 (ZTF) could become only just visible to the eye in dark night skies."

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How to observe C/2022 E3 (ZTF)

According to EarthSky, anyone in the Northern Hemisphere looking to observe C/2022 E3 (ZTF) should point their telescopes or binoculars low on the northeastern horizon just before midnight on January 12.

The icy comet will actually make its closest approach to Earth between February 1 and 2, when it will come within about 26 million miles (42 million kilometers) of our planet. During this period, sky-watchers should be able to spot the comet near the star Polaris, which is also known as the North Star, early in the evening.

NASA also points out that the comet should be visible through binoculars in the morning sky for most of January in the Northern Hemisphere. In the Southern Hemisphere, the same will be the case, though it will be visible in early February.