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Image: Ozkan Bilgin/Anadolu/Getty ImagesSkywatchers have witnessed several extraordinary celestial events this year, including total eclipses, meteor showers, and the aurora borealis. Now, there’s anticipation for another dazzling sky event: a particularly bright 'Halloween comet' passing by the sun, which might be visible across the Northern Hemisphere in late October or early November.
Sadly, the comet might break apart before it’s visible. But if it survives its close encounter with the sun, it could become one of the brightest comets since 2011 and might even be visible during the day. Here’s when you should look to the skies for this unpredictable spectacle.
About the Halloween Comet
Discovered in September during the ATLAS survey in Hawaii, the Halloween Comet has been officially named C/2024 S1 (ATLAS). It is believed to be a Kreutz sungrazer comet, a type of comet that travels very close to the sun, which can cause it to brighten significantly, though it also makes it prone to fragmentation or even disintegration.
On October 28, the comet is expected to come within just 190,000 miles of the sun's surface. Astronomers have observed signs of the comet fragmenting, creating uncertainty about whether it will remain visible.
Viewing Between October 23 and November 1
Despite the fragmentation, observers in the Southern Hemisphere will be able to view the comet beginning October 23, when it will be closest to Earth. It is anticipated to grow brighter each day from October 24 to October 28, with the most spectacular sight expected just before sunrise.
The comet will reach its perihelion, the point where it is closest to the sun, on October 28. If all goes as planned, it should become visible in the Northern Hemisphere at dusk starting October 29 and continue through December. Should it survive its close approach, astronomers predict that the comet could outshine Venus, making it easily visible during daylight hours.
Another Comet to Watch
In the coming days, astronomers will have more information about whether the comet will survive its close pass by the sun. If it breaks apart, nothing will be visible beyond October 28. (Viewing in the Southern Hemisphere will also be less bright.) Skywatchers will have to wait until the end of the month to learn if the comet will appear in the North, but the anticipation is expected to be worth it.
If you're unable to catch a glimpse of this comet, there's another one to check out—the C/2023 A3 Tsuchinshan-ATLAS comet. It was at its brightest around October 16 and remains visible through early November. (While it won't be visible during the day, you can still spot it at night.) Use Stellarium Web to map out either comet from your location.
