CAPE CANAVERAL, Fla. (AP) – A comet is hurtling back to us after 50,000 years.
According to NASA, the dirty snowball was last visited in Neanderthal times. It will come within 42 million kilometers of Earth on Wednesday before speeding away again and is unlikely to return in millions of years.
So look up, contrary to the title of the killer comet movie Don’t Look Up.
Discovered less than a year ago, this harmless green comet can already be seen with binoculars and small telescopes in the northern night sky, and possibly with the naked eye in the darkest corners of the northern hemisphere.
Expected to brighten as it approaches and rise higher above the horizon by late January, best seen in the hours before sunrise. By February 10, it will be near Mars, a good landmark. Skygazers in the Southern Hemisphere will have to wait until next month for a look.
While many comets graced the sky over the past year, “this one probably seems a little bit bigger and therefore a little bit brighter and getting a little bit closer to Earth orbit,” said NASA’s comet and asteroid tracking guru. Paul Chodas.
Green with all the carbon in the gas cloud, or coma, surrounding the nucleus, this long-period comet was spotted last March by astronomers using the Zwicky Transient Facility, a wide-field camera at Caltech’s Palomar Observatory.
That explains its official, unwieldy name: Comet C/2022 E3 (ZTF).
On Wednesday, it will race 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 1 mile (1.6 kilometers) in diameter, while its tails stretch for millions of miles (kilometers).
The comet is not expected to be anywhere near as bright as Neowise in 2020 or Hale-Bopp and Hyakutake in the mid to late 1990s.
But “it will be bright because of its close transit through Earth…allowing scientists to do more experiments and allowing the public to see a beautiful comet,” University of Hawaii astronomer Karen Meech said in an email.
Scientists are confident their orbit calculations place the comet’s last swing through the solar system’s planetary neighborhood at 50,000 years ago.
But they don’t know how close it got to Earth or if it was even visible to Neanderthals, said Chodas, director of the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory in California.
When it returns, however, it’s harder to judge.
Each time the comet orbits the sun and planets, their gravitational pulls change the ice ball’s path very slightly, causing large course changes over time. Another joker: Jets of dust and gas pour out of the comet as it heats up near the Sun.
“We don’t know exactly how much they’re pushing this comet around,” Chodas said.
The comet – a time capsule from the forming solar system 4.5 billion years ago – emerged from what is known as the Oort Cloud far beyond Pluto. This deep-freeze haven for comets is thought to extend more than a quarter of the way to the nearest star.
Although Comet ZTF formed in our solar system, we can’t be sure it will stay there, Chodas said. If it’s booted 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 them,” Chodas said. “And the next one might be bigger, might be brighter, might be closer.”
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