Fastest comet ever recorded comes from beyond our solar system

NASA’s Hubble Space Telescope has snapped images of a recently discovered interstellar visitor hurtling through our solar system. Traveling at 130,000 mph, 3I/ATLAS is the fastest comet ever observed by astronomers—the comet’s velocity hints at its ancient origins, as well as its potential impending, fiery fate.

The NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) space telescope installed in Rio Hurtado, Chile, initially detected the comet on July 1. Additional observations and analysis soon confirmed it’s only the third known object to pass through our solar system from deep space ever. In this case, it likely originated in an unknown star system far across the Milky Way galaxy—but don’t expect astronomers to get more specific.

“No one knows where the comet came from. It’s like glimpsing a rifle bullet for a thousandth of a second,” Hubble observations science team leader David Jewitt said in a statement. “You can’t project that back with any accuracy to figure out where it started on its path.”

Despite all that speed, Jewitt and his colleagues were still able to aim the Hubble telescope at 3I/ATLAS to get a better look. The results offered experts a trove of additional data to examine while assessing more details about the comet. Based on their calculations, the speedy icy mass may be anywhere from around 1,000 feet to 3.5 miles wide.

The Hubble telescope also provided a closer look at the comet’s dust plume ejecting on the object’s sun-warmed side, as well as a glimpse of the dust tail coming off the comet’s central nucleus. Further analysis of its dust-loss rate is consistent with previous comets seen about 300 million miles from the sun. Experts theorize that billions of years ago, 3I/ATLAS either spun out from a developing proto-planet system, or broke off a small planet after getting too close to a white dwarf star. But although the physical characteristics match up, one thing is markedly different from past examples—its speed.

To reach a velocity of 130,000 mph, 3I/ATLAS must have passed through multiple gravitational slingshots as it traveled near stars, planets, and nebulae over billions of years. Each encounter tacked on even more speed until it eventually attained its current rate. Basically, the faster the comet, the older it likely is.

3I/ATLAS will pass nearest to the sun in October 2025—but this meetup may be the comet’s final cosmic encounter. By the end of the month, it will come within 130 million miles of the star, just inside Mars’ orbit. 3I/ATLAS will remain visible to ground telescopes through the end of September, at which point it will be too close to the sun to see. 

And that may be it for the ancient comet. There is a chance the sun’s immense gravitational pull may be too strong for it to handle. If so, 3I/ATLAS will ultimately break apart and disintegrate like innumerable comets before it. However, if it manages to survive the ordeal, it will come out even more impressive. Similar to its slingshots of eons past, the comet will gain even more velocity, likely breaking its own speed record as it finally leaves our solar system. There’s also no need to worry—NASA says there’s no chance the come will swing around and cause any problems for Earth.

Astronomers should find out the comet’s fate in December 2025, when 3I/ATLAS will become observable once again—if it survives its likely biggest challenge yet, our sun.

 

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