Rare Green Comet To Make Appearance For The First Time In 50,000 Years

ACROSS AMERICA — If you see what looks like a green snowball streaking across the skies in the in the coming days, it’s likely Comet ZTF, which hasn’t been this close since the Upper Paleolithic period when Neanderthals roamed Earth.

And once its flyby is complete, Comet C/2022 E3 ZTF, as it’s officially known, won’t come our way again for another 50,000 or so years, according to NASA’s Jet Propulsion Laboratory. Although ancient with its last sighting in the last glacial “ice age,” the comet was only discovered last spring.

Comet ZTF has already reached perihelion, its closest approach to the sun (100 million miles), and may be visible even without binoculars under clear, dark skies, according to NASA. It will reach perigee, its closet approach to Earth, on Feb. 1, when it will be about 26 million miles away. By mid-February, the comet will zoom out of sight, according to NASA.

Be aware, though: “Comet brightness is notoriously hard to predict, though,” according to NASA. They often fail to measure up to predictions about brightness, or they may exceed expectations.

Some astronomy experts think the comet could be pulled back by the sun’s gravity, while others think the orbit’s eccentricity — its deviation from a perfectly round path — is strong enough to throw it off course into the vast universe, where it will hurtle through space indefinitely, NPR reported. It could also remain on its elliptical orbital path and come back around in tens of thousands of years.

That makes its close approach to Earth a once-in-a-lifetime opportunity.

“Countless long-period comets have never been seen by human eyes,” NASA told CBS News. For some, the agency said,“ the last time they passed through the inner solar system, our species did not yet exist.”

When Is The Best Time To Look?

Telescopes and binoculars will offer the best views of the comet in the morning sky as it moves northwest, according to Space.com. With a telescope, skywatchers can expect to see the comet through mid-February.

The comet is expected to brighten as it moves out of the Corona Borealis constellation this week and passes through the constellations Boötes, Draco, Ursa Minor and eventually Camelopardalis in its close approach to Earth. Track Comet ZTF’s movements on Universe Today.

The comet will be visible all night long by the time the last week in January rolls around. The Saint Louis Science Center advises serious comet watchers to look in the sky now. The moon, which reaches its full phase on Feb. 6, is about 50 percent illuminated this weekend as Comet ZTF makes its flyby of Earth.

A featured image of Comet ZTF on the NASA site last week offers a good look, showing three blue ion tails and a green glow in the comet’s coma, or nucleus, that is caused by glowing carbon gas. The comet will pass nearest to Earth on Feb. 1, then begin to dim dramatically through mid-February, when it will be gone from our viewing area on Earth, according to NASA.

At about one-sixth of a mile wide, the comet is smaller than the last significant comets to buzz Earth — Comet Neowise, which passed by in 2020, and Hale-Bopp, which swept by in 1997. Comet ZTC will come closer to Earth than either Neowise or Hale-Bopp, and experts say that could offset its size.

Ancient, But Newly Discovered

The comet is known as ZTF because astronomers at the National Science Foundation’s Zwicky Transient Facility in California using a wide-field camera at CalTech’s Palomar Observatory in San Diego County were the first to observe it last March. It was first thought to be an asteroid, but it as became brighter as it entered the inner orbit of Jupiter, astronomers determined it was a comet. At the time, it was 397 million miles from Earth.

Scientists believe the comet was born in the Oort Cloud, which NASA says is believed to be the source of most long-period comets and is “like a big, thick-walled bubble made of icy pieces of space debris the sizes of mountains and sometimes larger.” It may contain billions, or even trillions of objects.

Comet ZTC is one of 73 discovered in 2022, according to Universe Today. It’s also one of a dozen comets to watch for in 2023. Among them, Comet 96P Machholz reaches perigee on Jan. 31, may be worth watching for through early February.

More Skywatching Events

Mars will stand still all night long Thursday as it ends its westward retrograde loop through the stars and returns to an easterly prograde motion above the bright, reddish star Aldebaran, the brightest in the constellation Taurus, and moves farther away from the Pleiades star cluster each night.

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Venus and Saturday will dance in a very close conjunction above the west-southwestern horizon for an hour after sunset from about Jan. 20-24. Venus, the brightest planet in our solar system, is climbing higher in the western sky after sunset each evening, while golden Saturn, a much dimmer planet, sinks closer to the sunset.

Catch a glimpse of Saturn soon if you’re interested, because it’ll be hard to find by month’s end. Venus, though, will shine brilliantly in the evening twilight through August.

We will experience another lunar occultation of Mars. On Jan. 30, a waxing gibbous moon will pass in front of Mars and obliterate it from our view. People living in the southern U.S. and points south should be able to see it.