A comet discovered last year — known as C/2023 A3 Tsuchinshan-ATLAS — is set to make a close approach to Earth in the coming days.
The snowy dirtball is nearly 2 miles in diameter and its tail of dust and gasses extends for tens of millions of miles, Bill Cooke, lead of NASA's Meteoroid Environment Office at the Marshall Space Flight Center in Huntsville, Alabama, told NPR.
It was first discovered in 2023 by observers at the Purple Mountain Observatory in China and an Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in South Africa. From the Oort Cloud, a spherical shell that surrounds the solar system and contains icy objects like comets, the comet will come within 44 million miles of Earth, NASA said.
How can I see it?
The comet will initially appear low on the western horizon in the glow of twilight about 45 minutes after sunset each day starting Saturday, Oct. 12, through the end of the month, Cooke said.
The comet can be seen without special equipment but the best view will be through a pair of binoculars.
“Comets look okay to the unaided eye, but with a pair of binoculars, they'll knock your socks off,” Cooke said. “It'll be really good in a pair of binoculars. So, if you got a pair of binoculars, why don't you bring those along and take a look at the comet.”
As the month continues, the comet will become higher in the sky each night as it moves away from the sun and out of the solar system — and will appear dimmer and become harder to see with eyes alone. The comet will fade either the week before Halloween or around Halloween depending on how bright it is, Cooke also said. After that, the comet can still be viewed for a few months — but with with a professional telescope.
If I miss it, when can I see it again?
Unfortunately, it's probably not going to happen for you. After the end of the month, the comet isn't expected to swing by again for 80,000 years, according to NASA.
And at this time there is no other comet projected to be visible in the near future.
“Bright comets are very rare and are usually newcomers to the inner solar system,” Cooke said.
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