The last time the comet was visible from earth was 50,000 years ago. It's only just making its way back into our solar system now.
Californian astronomers first got a glimpse of the comet in March of last year and have been keeping an eye on it since.
Why is the comet green?
Comets are made up of ice, rocks, frozen gas and dust. As a comet approaches the sun, it starts to warm up and shed particles, which causes a glow around the head called a coma.
USA Today explains, "C/2022 E3 (ZTF) 's colour comes from its molecular composition. It has dicarbon molecules, chemical compounds with two bonded carbon atoms, and cyanogen. Both of these glow green when exposed to sunlight."
How to see the green comet?
If you're in the Northern Hemisphere, you should be able to catch a glimpse of the green comet in January.
But for the rest of us in the Southern Hemisphere, your best chance of seeing it is February 1 or 2 during the early morning hours.
Seeing it with the naked eye might be tricky, though. If you can get your hands on a pair of 10x50 binoculars, that will be your best chance of seeing this once-in-a-lifetime event.