A rare green comet is passing Earth, and this could be humanity's last chance to see it. Stunning photos reveal what you might see if you look to the pre-dawn skies and spot the ball of frozen gas and dust shooting past this week.
Formally, the comet is called C/2022 E3 (ZTF), named for the Zwicky Transient Facility, which first discovered it in March. But skywatchers call it Comet ZTF for short.
This icy cosmic passerby is painting a green streak across the sky through the first few days of February, reaching its closest point to Earth on Thursday, skimming past from 27 million miles away. You probably need binoculars to spot it, under dark skies far from city lights.
If you catch Comet ZTF with a telescope, which would offer the clearest view, you could see something like this:
Many comets glow green like this. Laboratory research has linked this aura to a reactive molecule called dicarbon, which emits green light as sunlight decays it.
Though green comets occasionally pass Earth, this one won't return for about 50,000 years, if ever. That's how long it takes Comet ZTF to orbit the sun, which means that Neanderthals still walked the Earth when it last whizzed by, during the last Ice Age.
"We like viewing and photographing the comet because bright ones are not only rare, but beautiful like this one. The tails of comets are never two alike," Chris Schur, an amateur astronomer and night-sky photographer in Arizona, told Insider in an email. "[Comets] move amongst the stars from night to night, making them a challenge sometimes to just find."
Astronomer Gianluca Masi captured the footage below of Comet ZTF, with its moving background of stars, during a live feed of his telescope observations:
"Observing such an 'icy world' is always very fascinating," Masi told Insider via email. "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."
Want to see the green comet yourself? Go to a place with dark skies, far from city lights, and look to the North before dawn, after the moon has set. Use a telescope if you can, or at least bring binoculars. Unless you're under very, very dark skies, the comet may not be visible to the naked eye.
According to EarthSky.org, the comet is carving a path past the constellations Ursa Major and Ursa Minor.
"Keep in mind that the light from a comet is not a bright point, but a fuzzy, diffuse spot. So, train your eyes to look for the lighter haze on the background sky and you might see it," professional skywatchers at EarthSky wrote.
They recommend scanning the northern sky with binoculars until you spot the comet, then try to see it with your unaided eye.
