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First time in 50,000 years green comet commeth; and it may never return again

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Comet C/2022 E3 (ZTF). Image: Dan Bartlett/Courtesy of NASA.

An ancient green visitor recently entered our solar system for the first time in 50,000 years; and will fly by Earth close enough to possibly be seen by the naked eye at the beginning of February.

Talk about a once-in-a-lifetime event. And, it may also be the last time ever. Some astronomers predict once the comet leaves our solar system, it could be flung into the universe, never to be seen again.

Astronomers have tracked comet C/2022 E3 (ZTF) since March 2022 when it was almost 400 million miles from the sun. The comet was discovered by astronomers at the Palomar Observatory in San Diego County, Calif., and made its closest approach to the sun on Jan. 12.

By the end of last year, the comet was approaching the inner solar system and was visible near the North Star through a telescope.

It will be closest to Earth, a little more than 26 million miles away, on Feb. 1 and 2, which also will be the best time to try and catch a view, according to the ‘Imiloa Astronomy Center of Hawai‘i in Hilo.

From The Virtual Telescope Project website.

Since its discovery, the comet has steadily brightened as it approached the sun.

The faint comet is visible in the northern sky through a telescope or a good pair of binoculars. Late this month and early next month, it could be visible with the naked eye under dark, clear skies; however, the astronomy center said the brightness of comets can be difficult to predict because much of it is based on the amount of ice on the object.

“Comets are notoriously unpredictable,” said Edward M. Murphy, a University of Virginia astronomer, in a UVAToday article. “Based on the behavior of past comets and their distance from the sun and Earth, we can usually predict with some accuracy how bright comets will be. That said, every now and then a comet brightens much more than expected and puts on a great show. There is no way to know what this comet will do since it has not been observed in recorded history.”

Comet C/2022 E3 (ZTF) closest approach to Earth on Feb. 1. Credit: NASA/JPL Small Body Database

The last time the comet visited the solar system 50 millennia ago, Neanderthals and modern humans lived alongside each other with at least two other types of humans, Homo floresiensis and Denisovans. Our ancestors also shared the planet with the likes of saber-toothed tigers and mammoths.

“This comet hasn’t been seen in 50,000 years … ,” said Mike Lundquist, a staff astronomer at W.M. Keck Observatory on the Big Island. “It spends most of [its] time out in the dark, frozen space well beyond the orbit of the planets.”


“Some predictions suggest that the orbit of this comet is so eccentric it’s no longer in an orbit — so it’s not going to return at all and will just keep going,” Jessica Lee, an astronomer at Royal Observatory Greenwich, told Newsweek.

The comet’s orbit has shifted since then, enough that astronomers think this could be the last time C/2022 E3 (ZTF) passes by Earth. The sun’s gravity has flung it on an open path that will never come back around, according to an article by SYFY.

At first, astronomers thought the comet was an asteroid. They identified it as a comet after observing a small green glowing coma, or envelope around the comet that forms as it passes close to the sun and its ice becomes gas. That causes the comet to look fuzzy when seen through telescopes.

“Comets are referred to as ‘dirty snowballs,'” Lundquist said. “They are made up of ice and dust and rocks, remnants from the formation of the solar system. As these comets get close to the sun, the solar radiation boils the outer layers of ice off, which we see as a comet tail.”

Lundquist added that studying the tail not only allows astronomers to learn about a comet’s composition but also the composition of the early solar system. It’s the streaking tail of ice, dust and rocks that distinguishes the comet from stars in the night sky.


Comet C/2022 E3 (ZTF) is incredibly dim. ‘Imiloa Astronomy Center said earlier this month that at its current rate of brightening, it would be twice as faint as the Andromeda galaxy at its brightest. So observers will need to know exactly where to look in that dark section of the sky on Feb. 1 and 2 and gaze for a good minute or two to have a chance to see the comet with the naked eye.

“I want to emphasize that the comet is not currently visible to the naked eye and there is a possibility that it might become visible to the naked eye, but even if it does it will be exceptionally faint and not obvious to find in the sky,” said Emily Peavy, senior planetarium educator and technician at ‘Imiloa.

At the comet’s closest approach to Earth, observers can find it in the sky about 20 degrees away from the North Star in the faint constellation of Camelopardalis.

No matter how you see it, don’t miss this rare chance. If the comet returns, it won’t be back for at least another 50,000 years.

TheSkyLive.com can help people track the comet, and The Virtual Telescope Project will livestream the comet at its closest point to Earth. You also can check out images and a short animation of the comet from Jan. 14 by visiting The Virtual Telescope Project website.

“Observing such an ‘icy world’ is always very fascinating,” Gianluca Masi, an astronomer with The Virtual Telescope Project, told Insider. “Comet C/2022 E3 ZTF reminds us, with its beauty, that those objects are the most elegant ones up there and we cannot simply miss the opportunity to have a look.”

Nathan Christophel
Nathan Christophel has more than 20 years of experience in journalism, starting out as a reporter and working his way up to become a copy editor and page designer, most recently at the Hawaii Tribune-Herald in Hilo.
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