Green comet visible over Western Pa. tonight if clouds cooperate

Shirley McMarlin, Tribune-Review, Greensburg, Pa.
·2 min read

Feb. 1—The so-called green comet will make its closest approach to Earth in about 50,000 years tonight, but whether you'll see it in the skies above Western Pennsylvania is debatable.

"Unfortunately, we're going to have increasing cloudiness overnight," said Lee Hendricks, a meteorologist with the National Weather Service in Moon.

"Some of those clouds will be thin, so there's a chance you might see it," he added. "I give it a 50-50 peak chance."

If the weather cooperates, viewers in the Northern Hemisphere who can find a spot away from significant light pollution will be able to see it, albeit faintly, without a telescope.

They will need to look to the northern sky between the Big Dipper and the North Star. It will be visible as a fuzzy smudge of light, possibly with a greenish cast.

If the atmosphere doesn't allow for naked-eye viewing, they can check out Live View of Comet C/2022 E3 on YouTube or tune in to the Virtual Telescope Project's livestream beginning at 11 p.m.

The comet, known to astronomers as C/2022 E3 (ZTF), will come within 26.4 million miles of Earth tonight, its closest approach in about 50,000 years, stretching back to the Neanderthal age. It is traveling at about 128,5000 miles per hour.

Its greenish hue comes from the gas that makes up the coma, a temporary atmosphere surrounding its rocky core.

When a comet streaks past a star, energy from the star — in this case, the sun — vaporizes the comet's ices into gas, forming the coma. The color of that coma comes from the type of gas present.

Some of the gas around C/2022 (ZTF) contains diatomic carbon. When those molecules are hit by ultraviolet radiation, they glow green.

The green comet was spotted last March by astronomers using the Zwicky Transient Facility at the Palomar Observatory in California. It isn't expected to make another pass by Earth for millions of years.

Shirley McMarlin is a Tribune-Review staff writer. You can contact Shirley by email at smcmarlin@triblive.com or via Twitter .