A glowing green comet zipped past the Earth during its elongated orbit around the sun 50,000 years ago. Now, it has finished that orbit and is again passing Earth, making it a once-in-a-lifetime sight for stargazers. 

According to Francisco Guzman Fulgencio, assistant professor of physics and astronomy at the University of North Georgia, the C/2022 E3 (ZTF) comet, nicknamed the “green comet,” will be most visible this week. 

“Now it’s passing closest to us just across the plain where the earth is moving and it’s going away from us, but this week is the best time to see it with the naked eye,” Fulgencio said. “In 4-5 days you will need a telescope and in a few weeks you’ll need big telescopes.” 

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Comets have an orbit that is elongated, he said, so for most of their orbit they’re far away from the earth. This comet is unique in that its orbit is so elongated it hasn’t passed the earth in 50,000 years. 

“It passed 50,000 years ago when there were Neanderthals on the earth,” Fulgencio said. “It’s very interesting because it has such a big elongation. Halley’s Comet, for comparison, has about a 70-year elongation.” 

The comet gets its bright green hue from its interaction with the sun. 

“The comet looks green because the comet is a big snowball, so when it gets close to the sun there is a lot of UV radiation from the sun and that is breaking up the organic molecules,” Fulgencio said. “So what you’re seeing is Carbon 2, C2, which is excited by the UV rays of light and emits green.” 

The comet has both a long faint ion tail and a short broad dust tail coming off of it, which is caused by this erosion of the comet by the sun as it flies past.

“A comet is like a dirty snowball and the sun emits particles that erode the comet,” Fulgencio said. “The comet is going around the sun and leaving a trail of dust, so we can see the trail of dust on its trajectory.” 

The comet will be most visible in the evening of Feb. 1 and into the early morning hours of Feb. 2. 

“With your naked eye it’s just on the limit of visibility, but you probably can see a small spot in the sky; with binoculars you may see the tail,” Fulgencio said. “It’s going to be visible the whole night but probably better during the early hours.” 

It will remain visible for the next several days with the naked eye, he said, and then for the next few weeks with the aid of a telescope. 

If the weather is clear on Friday, Feb. 3, UNG will be opening its observatory, located at 3000 Dawsonville Highway in Dahlonega, from 8 p.m. to midnight to allow the public to view the comet through the observatory’s telescopes. Any updates on conservatory hours and changes due to weather will be posted on social media at https://www.facebook.com/UNGObservatory/. 

More information about the comet, including its current position in the sky, can be found online through The Sky Live at https://theskylive.com/where-is-c2022e3. The Virtual Telescope Project will also be providing a live stream observation of the comet’s flyby on Youtube beginning at 11 p.m. on Wednesday, Feb. 1.