A bright green comet may be visible with the naked eye starting later this month

January 8th, 2023

Comet C/2022 E3 (ZTF) was discovered by astronomers using the wide-field survey camera at the Zwicky Transient Facility in March 2022. (Dan Bartlett/NASA)
Dan Bartlett / Dan Bartlett

A comet known as C/2022 E3, marked by its bright green nucleus and long faint ion tail, will be on display in the Earth sky later this month — possibly for the first time ever or at least for thousands of years.

“If C/2022 E3 has ever passed through the solar system before, it would have last been seen in the sky more than 10,000 years ago,” says Jon Giorgini, a senior analyst at NASA’s Jet Propulsion Laboratory.

Comets are essentially clumps of frozen gases, rock and dust. But when they approach the sun and heat up, they become powerful cosmic objects, spewing gases and dust in a way that forms their iconic shape: a glowing core and flame-like tail that can stretch on for millions of miles.

Astronomers first spotted the brightening outburst back in March 2022 at the Zwicky Transient Facility on Palomar Mountain in California. At the time, the comet was inside the orbit of Jupiter.

According to NASA, the newly discovered comet is expected to reach its closest proximity to the sun on Jan. 12. Then, about three weeks later, beginning Feb. 1, the comet is slated to draw nearest to Earth — 26.4 million miles away to be exact.

The brightness of comets tends to be unpredictable, but this one’s current behavior is promising, according to a recent explainer from Preston Dyches from NASA’s Jet Propulsion Laboratory. Its glow may be visible to the naked eye, though only in dark night skies. Observers with binoculars or telescopes have a greater chance of witnessing the rare speck of light.

Spectators in the Northern Hemisphere can begin to spot the comet’s faint glow in the morning sky this month, as it journeys toward the northwest, according to Dyches. The comet will likely be visible to those in the Southern Hemisphere starting early February.

After its brief appearance in the Earth skies, it’s unclear where it may go.

Because scientists have only recently begun to track the comet’s path, there is still a lot to understand about C/2022 E3, says Giorgini.

It’s possible it may gain enough energy to fling out of our solar system, or it might remain bound to its elliptical orbit for another trip around the sun.