Starting January 12, 2023, stargazers will get a once-in-a-lifetime chance to see a rare comet with a greenish hue. Astronomers discovered Comet C/2022 E3 (ZTF) in March 2022 when it was inside Jupiter's orbit. NASA scientists believe this may be the comet's first sighting. If the icy body did pass our planet previously, it was probably thousands of years ago.