A newly discovered comet, C/2024 S1, may put on a dramatic sky show in late October, but only if it survives its close pass with the Sun. First detected in September 2024 by the Asteroid Terrestrial Impact Last Alert System (ATLAS) in Hawaii, the comet is expected to reach peak brightness around October 24, possibly outshining Venus. Yet astronomers warn the object could break apart before reaching that stage.
Nicknamed the “Halloween Comet” by Forbes, C/2024 S1 is drawing attention because it follows closely on the heels of Comet Tsuchinshan-ATLAS, making 2024 a rare year with two bright comets visible to the public. NASA said the comet could briefly become visible in daylight near the Sun on October 24, especially from the U.S. East Coast. After Halloween, it is expected to reappear in the western evening sky from November 2 through mid-December.
The best viewing, however, will be from Africa, Europe, and South America, according to astronomers. Skywatchers in those regions may be able to see the comet without special equipment if it brightens enough. For others, binoculars or small telescopes will improve the view.
Still, its future is uncertain. The Watchmen Earth and Space Connection reported that the comet’s brightness has been fluctuating by about two magnitudes, a sign its icy core could be unstable. If the nucleus fractures while approaching the Sun, it may fade or even vanish completely, leaving only fragments behind.
On the other hand, if it holds together, the comet could become as bright as magnitude –5, far brighter than Venus, and visible in the pre-dawn skies of the Northern Hemisphere. Such brightness would make it one of the most striking comets in recent decades.
Scientists also believe C/2024 S1 may not be entirely new. Research suggests it could be a surviving fragment of the Great Comet of 1106, which broke apart more than 900 years ago during a close approach to the Sun. Like that historic comet, C/2024 S1 is thought to have originated in the distant Oort Cloud, a region of icy bodies at the edge of the solar system.
For now, astronomers are watching closely to see whether the so-called Halloween Comet makes it through its brush with the Sun. Its survival could mean a rare treat for skywatchers across several continents.