CAPE CANAVERAL, Florida (AP) – 50,000 years later, a comet is returning our way.
According to NASA, the dirty snowball was last visited during the time of Neanderthals. It will come within 26 million miles (42 million kilometers) of Earth on Wednesday and will accelerate away again, unlikely to return for millions of years.
So, look up, contrary to the name of the killer comet movie: “Don’t Look Up.”
Discovered less than a year ago, this harmless green comet can be seen with binoculars and small telescopes in the northern night sky and possibly the unaided eye in the darkest corners of the Northern Hemisphere.
Expected to light up by the end of January as it approaches and rises above the horizon, it’s best seen in the pre-dawn hours. By February 10 will be close to Mars, which is a good turning point. Skywatchers in the Southern Hemisphere will have to wait for a moment next month.
Although many comets have graced the sky over the past year, NASA’s comet and asteroid tracking guru said, “this one is probably a little larger and therefore looks a little brighter and comes a little closer to Earth’s orbit.” Paul Chodas.
Green from all carbon in the gas cloud or coma surrounding the core, this long-period comet was discovered by astronomers last March using the Zwicky Transient Facility, a wide-field camera at Caltech’s Palomar Observatory.
That explains its official, cumbersome name: comet C/2022 E3 (ZTF).
On Wednesday, it will swing 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) in diameter, with tails extending millions of miles (kilometers).
The comet is not expected to be as bright as Neowise in 2020 or the Hale-Bopp and Hyakutake in the mid-1990s.
But “it will be bright thanks to its close pass to Earth, allowing scientists to do more experiments and the public to see a beautiful comet,” University of Hawaii astronomer Karen Meech said in an email.
Scientists rely on orbital calculations that place the comet’s last spin in the solar system’s planetary neighborhood 50,000 years ago.
Chodas, director of the Center for Near-Earth Objects Studies at NASA’s Jet Propulsion Laboratory in California, said they don’t even know how close it got to Earth or whether it was seen by Neanderthals.
But when it comes back, it’s harder to judge.
Each time the comet circles the sun and planets, their gravitational pull changes the ice ball’s path slightly, resulting in major course changes over time. Another wild card: jets of dust and gas emanating from the comet as it heats up near the Sun.
“We don’t know exactly how far they pushed this comet,” Chodas said.
A time capsule from the solar system that arose 4.5 billion years ago, the comet came from what is known as the Oort Cloud, far beyond Pluto. This deep-freezing paradise for comets is believed to extend more than a quarter of the way to the next star.
Although comet ZTF originated in our solar system, we can’t be sure it will stay there, Chodas said. He added that if he leaves the solar system, he will never return.
If you miss it, don’t worry.
“In the comet business, you wait for the next one because there are dozens of them,” Chodas said. “And the next one might be bigger, it might be brighter, it might be closer.”
The Associated Press Department of Health and Science has support from the Howard Hughes Medical Institute’s Science and Education Media Group. AP is solely responsible for all content.
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