For the past year, scientists have been watching a brilliant green comet approaching Earth. While it’s already visible to the naked eye, the comet will reach its nearest (and brightest) point on February 2, making this the best weekend to see it.
The comet, which is called “C/2022 E3 (Z.T.F.),” last passed earth about 50,000 years ago. You should be able to spot it from anywhere in the Northern Hemisphere—simply look for a small green smudge about halfway between the North Star and the cup of the Big Dipper. If you have a good pair of binoculars or a compact telescope, you may also be able to catch a glimpse of its long emerald tail.
So, why the green color? Comets are massive chunks of ice, dust, and debris that originate in deep space where temperatures can be as low as -454°F. When a comet gets caught in a gravitational pull that tugs it closer to the sun, it begins to melt. As the ice falls away and the inside of the comet warms up, it releases gasses and reactive elements, which trail behind the comet in a glowing tail that can be millions of miles long. This particular comet is a unique color because it contains diatomic carbon, a molecule that emits green light when it absorbs UV radiation from the sun.
For the best chance of seeing C/2022 E3 (Z.T.F.), try going outside early in the morning when the moon is low on the horizon and won’t interfere with viewing. It’s also best to go somewhere far away from light pollution—making this the perfect excuse to plan a night hike.
If you can, drive into the mountains, local farmland, or a state or national park near you. Because viewing is best in the wee hours of the morning, consider making a weekend of it. Book a campsite, preferably without tree cover, and set an alarm for moonset. (You can look up moonset times for your location through the U.S. Naval Observatory website.) Then, crawl out of your tent, get the stove going for hot cocoa, and watch the sky for our newest celestial neighbor.