A stray comet from another star is swinging past Earth this week in one last visible hurrah before it races back toward interstellar space. Discovered over the summer, the comet, officially designated 3I/Atlas, will pass within 167 million miles (269 million kilometers) of our planet on Friday. This marks the closest point of its grand tour through our solar system.
NASA continues to aim its space telescopes at the visiting ice ball, which is estimated to be between 1,444 feet (440 meters) and 3.5 miles (5.6 kilometers) in size. Since the comet is fading as it exits, backyard astronomers should try to catch it now with their telescopes.
Future path of the comet
The comet will make a much closer approach to Jupiter in March, zipping within 33 million miles (53 million kilometers). However, it will be the mid-2030s before it finally reaches interstellar space, never to return, according to Paul Chodas, director of NASA's Center for Near Earth Object Studies.
This is the third known interstellar object to cut through our solar system. Interstellar comets like 3I/Atlas originate in star systems elsewhere in the Milky Way, whereas "home-grown" comets, such as Halley's Comet, hail from the icy fringes of our own solar system.
How the comet was discovered
The first confirmed interstellar visitor was discovered by a telescope in Hawaii in 2017. Two years later, a second interstellar comet was spotted by a Crimean amateur astronomer. Comet 3I/Atlas was observed in July by NASA's sky-surveying Atlas telescope in Chile while it was searching for potentially dangerous asteroids.
Scientists believe this latest interloping comet, which is also harmless, may have originated in a star system much older than our own, making it a particularly tantalising target for study.
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