This Rare Green Comet Is Approaching Earth for the First Time in 50,000 Years

Comet C/2022 E3 (ZTF) should already be visible through telescopes, and potentially even binoculars, however its closest approach will occur between Feb. 1 and Feb. 2.

Comet C/2022 E3 (ZTF), which was first spotted by astronomers in March 2022, is making its closest approach to Earth in an astonishing 50,000 years. That's how long astronomers think it takes for the comet to make a single orbit around the sun — it's what's known as a long-period comet, or a comet with an orbital period of more than 200 years.

The massive ball of ice and debris just hurtled around the sun, reaching perihelion (its closest approach to our star) on Jan. 12, and now it's headed towards Earth. But don't worry, it's not on a collision course with us. Its closest approach will occur between Feb. 1 and Feb. 2, when it will be more than 26 million miles away.

But the comet should already be visible through telescopes and potentially even binoculars, thanks in part due to the fact that the new moon coming up on Jan. 23 — the moon is waning, so it's creating less light pollution for stargazers. And if the comet brightens in the coming days, it might even be visible to the naked eye. In order to see it, you'll need to be far away from manmade light pollution.

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/Courtesy of NASA

"Observers in the Northern Hemisphere will find the comet in the morning sky, as it moves swiftly toward the northwest during January. (It'll become visible in the Southern Hemisphere in early February.)," according to a skywatching video by NASA's Jet Propulsion Laboratory. "This comet isn't expected to be quite the spectacle that Comet NEOWISE was back in 2020. But it's still an awesome opportunity to make a personal connection with an icy visitor from the distant outer solar system."

What makes this particular comet notable other than its long orbital period is the fact that it's glowing green, which is something of a rare color in space. Per EarthSky, that might be due to a specific chemical reaction of diatomic carbon molecules. But we know rather little about Comet C/2022 E3 (ZTF), so astronomers are taking this once-in-a-lifetime opportunity to study it.

According to Space.com, Comet C/2022 E3 (ZTF) likely originated in the Oort Cloud, a mysterious and vast region of space well beyond the outer reaches of our solar system. It's suspected to house millions, billions, or even trillions of icy bodies, many of which are comets. After rounding the sun, Comet C/2022 E3 (ZTF) is heading back in that direction, and astronomers aren't sure that the comet will ever return — changes in its orbit could send it flying in another direction, or the comet could break up entirely. Even if it does come back, it wouldn't do so for another 50,000 years, and chances are you won't be around to see it then.

If you're not in an optimal viewing location, or you don't have the right equipment to see the comet yourself, don't worry. The Virtual Telescope Project will be hosting a live stream starting at 11 p.m. EST on Feb. 1, which you can watch on its website or YouTube channel.

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