A green comet is passing by Earth for the first time since Neanderthals walked the planet and could be spotted by the naked eye. Believed to have been born in the farthest reaches of the solar system in an icy world dubbed the Oort cloud, C/2022 E3 is thought to orbit the sun every 50,000 years, meaning it last passed Earth when it was populated by the likes of Neanderthals and woolly mammoths, per the Guardian and Washington Post. Modern astronomers Bryce Bolin and Frank Masci first became aware of the comet in March 2022 when they used the Zwicky Transient Facility telescope in California to observe it in the orbit of Jupiter.
Nicknamed "the green comet" due to the color of its glowing nucleus—attributed to the sun's interaction with diatomic carbon at the head of the long-period comet—it has been visible with telescopes and binoculars for several days but will be best viewed on Wednesday and Thursday, when it makes its closest pass of Earth at a distance of 26 million miles, per NPR. "These kinds of comets that come this close or become this bright only come … every four or five years," Bolin tells the Post. Its green glow could be visible with the naked eye under clear, dark morning skies, per NPR.
Watchers in the Northern Hemisphere "can find the comet by looking south of the Big Dipper, near the constellation Camelopardalis," Bolin tells the Post. The green nucleus and coma around the nucleus will be about "half of the size of a full moon." It will be trailed by a faint ion tail, harder to see with the naked eye. If you don't catch the comet in the next couple of days, don't fret. It will remain visible by a "vast majority of the Northern Hemisphere and in the north direction" for the first half of February, Bolin says. It will near Mars on Tuesday, then travel south so that by the middle of the month, it will appear as if it is over the equator, he adds. (Read more comet stories.)