Saturn throws comet from solar system at dizzying speed: Here’s why

Astronomers believe they have discovered a fast-moving comet that Saturn sent careening out of our solar system at a speed far eclipsing humanity’s fastest fighter jets.
Though the planetary encounter occurred in 2022, it wasn’t until June that the team of scientists spotted the high-speed comet and analyzed the data to reach their conclusions.
In a paper published in July, astronomers determined that the comet was flung away from Saturn at a speed fast enough to send it on a hyperbolic trajectory, meaning it had the momentum required to exit our solar system and enter interstellar space. However, the comet’s origin before it came upon Saturn remains difficult to infer, the researchers wrote.
Could it possibly be another interstellar object passing through our solar system? Or is the explanation far more mundane?
Here’s what they learned about the celestial object, dubbed Comet A117uUD.
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Comet A117uUD was first spotted June 14 by the Asteroid Terrestrial-impact Last Alert System, or ATLAS.
For the next month, a team of astronomers made 142 observations of the object to get a sense of its path. What they discovered is that while orbiting the sun, the comet met up with the ringed planet of Saturn, our solar system’s second largest behind Jupiter.
But the meet-up with the gas giant was hardly inconsequential: Models showed that Saturn’s momentum effectively hurled the comet on an interstellar course at a speed exceeding 6,700 miles per hour, the team found.
For comparison, a Lockheed Martin F-16 can reach top speeds of about 1,345 mph.
At first glance, the comet appeared to be an interstellar object, which wouldn’t be the first time a celestial body visited from outside our solar system.
In 2017, the comet Oumuamua – Hawaiian for “scout” or “messenger” – became the first such interloper detected flying through the solar system, puzzling scientists due to its strange shape and trajectory.
In fact, the space rock was so mystifying that Harvard professor and theoretical astrophysicist Avi Loeb posited that the comet − as long as a football field and thin like a cigar − could be extraterrestrial in nature. Loeb’s theory rested on the notion that Oumuamua was able to accelerate as it approached the sun by harnessing its solar power as a “light sail,” not unlike the way a ship’s sail catches the wind.
Because no natural phenomenon would be capable of such space travel, Loeb, no stranger to theorizing about the interstellar origin of various objects, was essentially suggesting Oumuamua could have been an alien spaceship.
A study in March 2023 explained the comet’s odd orbit as a simple physical mechanism thought to be common among many icy comets: outgassing of hydrogen as the comet warmed in the sunlight.
Two years later, amateur astronomer Gennadiy Borisov discovered another comet from outside our solar system, Comet 2I/Borisov.
However, the team of researchers are now confident that Comet A117uUD originated from right here in our own solar system.
It’s now been confirmed as the second solar system comet to effectively be launched out of our solar system, becoming an interstellar object in its own right. The first was Comet C/1980 E1 (Bowell), which encountered Jupiter in 1980 and was similarly hurled out of the solar system, according to the astronomers’ study.
“The fact that two ejections after planetary encounter were observed in less than 45 years suggests that such events are relatively frequent,” the team concluded.
The team’s findings were published in the journal Research Notes of the AAS.
Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]