Don’t Miss Comet Tsuchinshan-ATLAS
By Graham Jones and Anne Buckle. Published 17-Oct-2024. Changed 23-Oct-2024
Want to find C/2023 A3 (Tsuchinshan-ATLAS)? Look in the western night sky just after sunset. We give you 5 steps to up your chances of spotting this rare naked-eye comet in the night sky.
UPDATE (October 23): Tsuchinshan-ATLAS is no longer a naked-eye comet, but may remain visible with binoculars for another month or so.
You can find and track Comet Tsuchinshan-ATLAS from your location using our Night Sky Map. This image shows the view from New York at 20:00 (8:00 pm) on October 18, 2024.
©timeanddate.com
Find Comet Tsuchinshan-ATLAS on our Night Sky Map
News update: Two comets in October?
Tsuchinshan-ATLAS Lights Up the Evening Sky
A bright comet with a strange-sounding name has been delighting evening skywatchers over recent weeks. It has been one of the brightest comets this century so far.
timeanddate.com’s Brendan Goodenough took this image of Tsuchinshan-ATLAS skimming above the mountains near Harstad, Norway, on October 19 (click to zoom in). Brendan’s photo also includes the aurora borealis—better known as the northern lights.
©Brendan Goodenough/timeanddate.com
C/2023 A3 (Tsuchinshan-ATLAS)—often referred to as Tsuchinshan-ATLAS, or simply A3—was discovered by astronomers at the beginning of last year.
The comet reached perihelion—its closest point to the Sun—on September 27, 2024. It is now traveling away from the Sun, which means it is getting higher and easier to spot in the western sky after sunset. At the same time, the comet is getting dimmer as it travels further from the Sun.
A 5-Point Comet Checklist
What do you need to see Tsuchinshan-ATLAS—one of the few comets you’ll be able to see with your naked eye in your lifetime? Here are five things that will help you get the best views.
- Clear skies—check your local weather.
- A good view to the western horizon—this is the direction where the Sun sets.
- Get away from light pollution—the darker the environment, the better, so get away from city lights if you can.
- Look for the comet after sunset—our Night Sky Map suggests the “best” time to see the comet, as well as the time the comet sets.
- Bring a pair of binoculars—magnification will improve your view.
Naked-Eye Comets Are Rare
Comets are small, icy bodies that mostly orbit the Sun in highly elliptical, or oval-shaped, orbits. When a comet passes close to the Sun, it warms up, and can produce a tail of gas and dust.
Thousands of comets have been discovered—but only a handful ever become visible to the naked eye. One of the most notable naked-eye comets in recent years was NEOWISE in 2020.
What Does the Name Mean?
The name C/2023 A3 (Tsuchinshan-ATLAS) is based on a set of rules from the International Astronomical Union.
- Comet C/ refers to a non-periodic comet. This means the comet hasn’t been observed before, and its orbital period (the amount of time it takes to complete one orbit around the Sun) is greater than 200 years. The orbital period of C/2023 A3 is thought to be around 80,000 years.
- 2023 is the year the comet was discovered.
- A indicates the half-month it was discovered. The first half of January is “A,” the second half of January is “B,” the first half of February is “C,” and so on.
- 3 means it was the third comet discovered in the first half of January.
- Tsuchinshan-ATLAS tells us it was discovered by two observatories. A system of robotic telescopes called the Asteroid Terrestrial-impact Last Alert System (ATLAS) spotted the comet on February 22, 2023. When the orbit of the comet was calculated, astronomers noticed it matched an object reported by the Purple Mountain Observatory in China on January 9, 2023. “Tsuchinshan” is a way of writing the Mandarin words for “Purple Mountain.”