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

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."

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.

Here's the path through our solar system that comet C/2022 E3 (ZTF) will take in the coming weeks. After that, fuhgeddaboudit! #comet #astronomy pic.twitter.com/OjrzQEXnXw

— CCNY Planetarium (@CCNYPlanetarium) January 10, 2023

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.