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Once in 50,000 years

The Green Comet approaches, and a UND astronomer explains how to see this breathtaking but exceptionally rare phenomenon

C-2022-E3-ZTF, or the Green Comet, will make its closest pass to the Earth in 50,000 years this week. Pictured is C/2014 Q2 (Lovejoy), a long-period comet discovered in August 2014 by Terry Lovejoy. Wikimedia Commons image.

Despite the frigid temperatures forecast for the nights of Wednesday, Feb. 1, and Thursday Feb. 2, stargazers might want to bundle up.

That’s because on those days, comet C/2022 E3 (ZTF) will make its closest pass to the Earth in 50,000 years. This press release will forgo the clunky nomenclature and simply refer to the object as the Green Comet, which, even after the first and second of the month, should remain visible at night for a portion of February, as it has been for the past few weeks.

For Sherry Fieber-Beyer, assistant professor of Space Studies at UND, tracking and researching such celestial bodies is one of the best parts of her job. From her fifth-floor office in Clifford Hall on campus, she’s able to connect to online resources that allow her to track where the comet is now, how far it is from the moon, and where it will be headed in the near and long-term future. And whether it can be seen by the casual observer.

“You can see it all night long,” Fieber-Beyer said. “It’s best in the early morning hours like at moon set (about 4 a.m.).”

Fieber-Beyer collects this information not only for her own use, but so her students — should they brave the cold — can get outside to look at an object that may be billions of years old, and that no living person on the planet has ever seen.

So why is it interesting?

According to Fieber-Beyer, the comet’s color is one thing that sets the object apart. Most comets show up as blue. But the Green Comet’s color comes from the comet’s being composed of carbon and nitrogen, Fieber-Beyer said.

Out in deep space and far from a star, those elements exist as ices. So, when the comet approaches a star such as the Earth’s sun, those element sublimate — in other words, change directly from a solid to gas — which gives the comet its long “tail.”

She isn’t sure about the rest of the Green Comet’s composition, though. In fact, no one is.

“I mean, no one’s looked at it before, right?” she said with a laugh.

The comet was discovered in 2022 at the Zwicky Transient Facility at the Palomar Observatory in California, all of which plays into the comet’s lengthy name. The comet’s composition could include some water and maybe some dust, materials that Fieber-Beyer calls the “primordial stuff” from when the solar system formed. She said she is certain research papers will begin to pop up in the wake of the Green Comet’s passing.

And then there’s the possibility that Neanderthals may have seen this comet 50,000 years ago. Given there was no light pollution at that time, no lingering hazy glow that illuminates the sky above a population center, the comet would have been visible — had those very distant cousins of today’s humans been looking.

Where’s it from? Where’s it going?

The answer to both questions is the same: the Oort Cloud, which according to NASA is the furthest region of our solar system, and is “a big, thick-walled bubble made of icy pieces of space debris the sizes of mountains and sometimes larger.”

The inner edge of the Oort Cloud is thought to be between 2,000 and 5,000 astronomical units (AU) from the sun. In contrast, the distance from the sun to Earth’s orbit is 1 AU, or about 93 million miles.

So, while it may originate from our solar neighborhood, the Green Comet isn’t exactly a next-door neighbor.

How do I see it?

Observers may want to head a short distance out of town to escape the light pollution, Fieber-Beyer said. Still, in Grand Forks it should also be visible, especially if one uses a pair of binoculars. Fieber-Beyer said she uses a spotting scope of the sort that hunters use.

Head outside and face north, she said. Look straight to the horizon, and using your arm, point straight in that direction, so your arm parallels the ground. Your other arm, raised straight above your head pointing at the sky makes a 90-degree angle from the horizon. Raise your arm that parallels the ground about 45 degrees and start your search in that area.

“If you have good eyes and you’re in a dark spot, you can see it,” she said. She clarified that people should not look for a moving point of light, but rather a green, extremely slow-moving “fuzzy dot.”

To make it easier, people can download a stargazing smartphone application called Stellarium Mobile. The app uses the smartphone’s camera to identify constellations — just move the phone and watch the screen. The Green Comet should be near the constellation Camelopardalis, a four-star figure that forms a giraffe.

A clear sky will be helpful in seeing the comet. According to the National Weather Service, the forecast on Wednesday night (Feb. 1) and Thursday morning is for “cloudy, then gradually becoming partly cloudy” skies. But that may be the best odds for stargazing that the week has to offer, given that the forecast reads “cloudy” or “mostly cloudy” for the other nights of the week.

Again, the comet should remain visible at night for part of February, should conditions this week not be the best to see it.

Fieber-Beyer said the sight will be worth braving the cold.

“It is not going to be back for 50,000 years, so it’s a once in a lifetime event,” she said.