A NASA astronaut released footage of a comet appearing above the horizon before sunrise surrounded by the glow of an aurora and moving satellites.
Comet C/2023 A3 Tschinshan-ATLAS will be at its closest point to Earth, 44 million miles, on Saturday, and should be visible to the naked eye in the western sky just after sunset. The comet will be visible through October, first without and later with binoculars. But once it moves away, it won't be back for 80,000 years.
"This weekend is going to be one of the better times to spot it; it's coming out of the sun's glare," said Shannon Schmoll, director of the Abrams Planetarium at Michigan State University.
Comets are large objects made of dust and ice that orbit the sun. Best known for their long, streaming tails, these ancient objects are leftovers from the formation of the solar system 4.6 billion years ago. The comet making its appearance now derived its name from those who first discovered it last year, the Tsuchinshan, or "Purple Mountain," Observatory in China and the ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope in South Africa.
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Tsuchinshan-ATLAS comes from the Oort Cloud, a barrier of icy debris around our solar system, well out past Pluto. Some comets come around Earth with relative frequency -- one known as Encke's Comet visits every 3.3 years. The famous Halley's Comet comes every 76 years. It was last visible from Earth in 1986 and will return in 2061.
But Tsuchinshan-ATLAS's orbit is highly elliptical, meaning it won't make a return visit to the inner solar system for another 80,000 years.
Because comets are composed of ice, many don't survive their close encounter with our sun. But Tsuchinshan-ATLAS survived its closest pass by the sun Sept. 27 and is moving on.
How to see it? Look to the west-southwest about 30 to 45 minutes after sunset and it should be low on the horizon, Schmoll said. Because it's so low, an unobstructed western view will help, she said. It should be in the vicinity of the bright star Arcturus and the bright planet Venus as they rise in the night sky, and should be between them by Monday.
"It should be visible throughout the rest of October as well, but as it continues to move it is going to get higher in the night sky but farther away from the sun, so less bright," Schmoll said. "By the end of October, you will probably need binoculars to view it.
"We are not going to see this particular comet again, and it is definitely worth going out to see."