Cape Canaveral, Fla. (AP) – A comet is returning to our path after 50,000 years.
According to NASA, the dirty snowball was last visited during the Neanderthal period. It will come within 26 million miles (42 million kilometers) of Earth by Wednesday, before speeding off again, unlikely to return for millions of years.
So, as opposed to the killer-comedy movie title, see “Never See.”
Discovered a year ago, this harmless green comet is already visible in the northern night sky with binoculars and small telescopes and with the naked eye in the darkest corners of the Northern Hemisphere.
As it approaches the end of January, it is expected to brighten as it rises over the horizon. By February 10, it will be close to Mars, which is a good sign. Skygazers in the Southern Hemisphere will have to wait until next month for a glimpse.
While plenty of comets have graced the sky in the past year, “this one looks a little bigger, and therefore a little brighter, and it’s coming a little closer to Earth’s orbit,” said NASA’s comet and asteroid observatory guru. Milk Sodas.
The long-lived comet, which is green from all the carbon in the gas cloud or coma surrounding the nucleus, was discovered last March by astronomers using the Swiggy Transient Facility, a wide-field camera at Caltech’s Palomar Observatory.
This explains its official, complicated name: Comet C/2022 E3 (ZTF).
On Wednesday, it will strike between the orbits of Earth and Mars at 128,500 mph (207,000 kilometers). Its nucleus is thought to be a mile (1.6 kilometers) across, and its tails stretch millions of miles (kilometers).
The comet is not expected to be as bright as Neowise in 2020, or as bright as Hale-Pop and Hyakutake in the mid-to-late 1990s.
But “it’s bright because of its close-to-Earth path…which allows scientists to do more experiments and the public to see the beautiful comet,” University of Hawaii astronomer Karen Meech said in an email.
Scientists are confident in their orbital calculations that the comet’s last swing through the Solar System’s planetary neighborhood was 50,000 years ago.
But they don’t know how close it came to Earth, or whether Neanderthals even knew it, said Sodas, director of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory in California.
When it comes back, the judgment is difficult.
Each time the comet orbits the Sun and the planets, their gravitational pulls alter the trajectory of the snowball ever so slightly, leading to larger changes over time. Another wild card: dust and gas escape as comets heat up near the Sun.
“We don’t know how much they’re pushing this comet around,” Sodas said.
The comet — a time capsule from the growing solar system 4.5 billion years ago — came from what’s known as the Oort Cloud beyond Pluto. This deep frozen refuge for comets is believed to extend over a quarter of the way to the next star.
Even if comet ZTF originated in our solar system, it’s not certain that it will stay there, Sodas said. If it leaves the solar system, it will never return, he said.
Don’t worry if you missed it.
“In the comet business, you wait for the next one, because there are dozens of these,” Sodas said. “The next one might be bigger, might be brighter, might be closer.”
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