Green comet zooming our way, last visited 50000 years ago - The Associated Press

It’s expected to brighten as it draws closer and rises higher over the horizon through the end of January, best seen in the predawn hours.

Green from all the carbon in the gas cloud, or coma, surrounding the nucleus, this long-period comet was discovered last March by astronomers using the Zwicky Transient Facility, a wide field camera at Caltech’s Palomar Observatory.

But “it will be bright by virtue of its close Earth passage ... which allows scientists to do more experiments and the public to be able to see a beautiful comet,” University of Hawaii astronomer Karen Meech said in an email.

Scientists are confident in their orbital calculations putting the comet’s last swing through the solar system’s planetary neighborhood at 50,000 years ago.

Another wild card: jets of dust and gas streaming off the comet as it heats up near the sun.

The comet — a time capsule from the emerging solar system 4.5 billion years ago — came from what’s known as the Oort Cloud well beyond Pluto.