Green comet approaching us, last visited 50,000 years ago

CAPE CANAVERAL, Fla. (AP) — A comet is headed our way after 50,000 years.

The dirty snow globe last visited during the time of the Neanderthals, according to NASA. It will come within 26 million miles (42 million kilometers) of Earth on Wednesday before speeding away, unlikely to return for millions of years.

So look up, contrary to the killer comet movie title “Don’t Look Up.”

Discovered less than a year ago, this harmless green comet is already visible in the northern night sky with binoculars and small telescopes, and possibly with the naked eye in the darkest corners of the Northern Hemisphere. It is expected to brighten as it approaches and rises above the horizon through late January, best seen in the pre-dawn hours. By February 10, it will be close to Mars, a good reference point.

Skygazers in the southern hemisphere will have to wait until next month to get a look.

While many comets have appeared in the sky over the past year, “this one seems probably a bit bigger and therefore a bit brighter and is getting a bit closer to Earth’s orbit,” the guru said. Comet and Asteroid Tracker at NASA, Pablo Chodas.

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. That explains its official and cumbersome name: Comet C/2022 E3 (ZTF).

On Wednesday, it will launch between the orbits of Earth and Mars at a relative speed of 128,500 mph (207,000 kilometers). Its core is thought to be about a mile (1.6 kilometers) wide, with its tails stretching millions of miles (kilometers).

The comet is not expected to be as bright as Neowise in 2020, or Hale-Bopp and Hyakutake in the mid to late 1990s.

But “it will be bright by virtue of its near-Earth pass … allowing scientists to do more experiments and the public to see a beautiful comet,” University of Hawaii astronomer Karen Meech said in an email. .

The scientists are confident that their orbital calculations place the comet’s last spin through the planetary neighborhood of the solar system at 50,000 years ago. But they don’t know how close it was to Earth or whether it was visible to Neanderthals, said Chodas, director of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in California.

When he returns, however, it’s harder to judge.

Each time the comet skirts the sun and planets, its gravitational tugs very slightly alter the path of the iceball, leading to major course changes over time. Another wild card: jets of dust and gas spewing from the comet as it heats up near the sun.

“We really don’t know exactly how far they are pushing this comet,” Chodas said.

The comet, a time capsule of the solar system emerging 4.5 billion years ago, came from what is known as the Oort Cloud far beyond Pluto. This frozen paradise for comets is believed to extend more than a quarter of the way to the next star.

Although the ZTF comet originated in our solar system, we can’t be sure it will stay there, Chodas said. If it is kicked out of the solar system, it will never return, he added.

Don’t worry if you miss it.

“In the comet business, you just wait for the next one because there are dozens of these,” Chodas said. “And the next one could be bigger, it could be brighter, it could be closer.”

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