Here's how to observe the green comet that last flew by Earth 50,000 years ago

It's the last chance any of us will have to see comet C/2022 E3 (ZTF), which may soon be visible with the naked eye.
Chris Young
Comet 2022 E3 (ZTF)
Comet 2022 E3 (ZTF)

NASA / Dan Bartlett 

A green comet called C/2022 E3 (ZTF) is set to pass by Earth for the first time in 50,000 years on February 1.

The last time it was in our vicinity, Earth was in the midst of an Ice Age, and Neanderthals still roamed the planet. According to scientists' calculations, the comet will never return to Earth again, as per a LiveScience report.

So viewing C/2022 E3 (ZTF) is a once-in-a-lifetime opportunity. Thankfully you can already view the comet before its closest approach to Earth. Here's how you can observe the green glowing space rock, whether in the northern or southern hemisphere.

How to observe comet C/2022 E3 (ZTF)

Starting yesterday, January 12, C/2022, E3 (ZTF) was at perihelion, meaning it was at its closest point to the sun. As it approached the sun, the comet developed a coma caused by increased heat sublimating ice straight into gas. A comet coma is a nebulous envelope that surrounds the space rock and is responsible for its green hue.

From the predawn hours of January 12, the comet should have been visible near the northern sky constellation Corona Borealis, and it should be located due west from that point over the next few days.

The comet should be viewable using a backyard telescope or a pair of binoculars. NASA has pointed out that, at its brightest, likely near the end of January, it may even be visible to the naked eye. "The brightness of comets is notoriously unpredictable," the US space agency pointed out on its website, "but by then, C/2022 E3 (ZTF) could become only just visible to the eye in dark night skies."

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For those who don't have ideal viewing conditions or live in an area strongly affected by light pollution, the Virtual Telescope Project also runs a live stream showing the comet from Earth.

During the nights of Jan. 26 and 27, the comet should be visible just east of the Little Dipper's bowl. C/2022 E3 (ZTF) will make its closest approach to Earth on February 1, when it comes within 28 million miles (45 million kilometers) of our planet. Around that time, it should be viewable near the constellation Auriga and the star Polaris, also known as the North Star.

NASA has also pointed out that C/2022 E3 (ZTF) should be visible through binoculars in the morning sky for most of January in the Northern Hemisphere. The same should also be the case in the Southern Hemisphere, though it will be visible in early February.

Astronomers the world over will wave goodbye to Comet C/2022 E3 (ZTF)

Comet C/2022 E3 (ZTF) was discovered on March 2, 2022, by astronomers Frank Masci and Bryce Bolin. They used the Zwicky Transient Facility’s wide-field survey camera at the Palomar Observatory in San Diego County, California. At the time of the discovery, the comet flew near Jupiter, roughly 400 million miles (643 million km) from the sun.

The comet has an incredibly long-period orbit that sees it pass through the outer reaches of the solar system as it nears its closest approach to Earth — which is why it hasn't been viewable in the night sky for roughly 50,000 years.

As Space.com points out, C/2022 E3 (ZTF) appears to have a parabolic orbit, also sometimes referred to as an escape orbit. In other words, once it makes its way around the sun, the green comet will likely zoom off into deep space and will never be seen near Earth again.