When you buy through links in our articles, Future and its syndication partners may earn commission.
Scientists have discovered a comet heading out of the Solar System after a close encounter with Saturn.
The comet, dubbed Comet A117uUD (A117uUD), was only discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) on June 14, 2024. However, researchers were able to “rewind” its orbit around the Sun using 142 observations of the comet. This revealed that A117uUD will meet Saturn, the second-largest planet in the Solar System and famous for its bright and prominent rings, in 2022, and will be changed forever.
The encounter with the gas giant placed the comet in a highly flattened, or elliptical, orbit that would launch it beyond the sun’s influence and into interstellar space. Using models to speed up A117uUD’s path, the team found that it would exit the solar system at about 6,710 miles per hour (10,800 km/h). That’s about four and a half times the top speed of a Lockheed Martin F-16 jet fighter.
This is only the second solar system comet we’ve seen in the process of being ejected from the solar system. The first was Comet C/1980 E1 (Bowell), which entered the solar system escape route after an encounter with Jupiter on December 9, 1980.
“Our results show that the situation of comet A117uUD is similar to that of C/1980 E1 (Bowell), which does not support an extrasolar origin for A117uUD,” the team writes in a paper published in the journal Research Notes of the AAS. “The fact that two ejections were observed less than 45 years after the planetary encounter suggests that such events are relatively frequent.”
Relating toA comet approaching Earth could shine brighter than stars this fall
Make up your mind. Are you coming or going?
It wasn’t always clear that A117uUD was a solar system body doomed to leave its home planetary system. When the team behind this discovery first analyzed the icy space rock, they thought its hyperbolic orbit might indicate it was actually an intruder into our solar system.
The first Solar System intruder discovered by humanity was the strange cigar-shaped asteroid 1I/’Oumuamua (‘Oumuamua), which means “first messenger from afar” in Hawaiian.
When discovered in 2017, ‘Oumuamua immediately caught the attention of astronomers due to its highly unusual shape and appearance as a strange comet/asteroid hybrid, but its lack of a coma (the halo surrounding comets) or obvious cometary tail. It was also moving away from the Sun, leading to the claim that this visitor from another planetary system could be an alien spacecraft (mostly) now being dismissed.
The solution to these unique features is that ‘Oumuamua was roasted by cosmic radiation before it reached the solar system, which caused hydrogen to be created and trapped inside its body. This hydrogen was released and began to erupt out of the space rock when ‘Oumuamua reached the relative temperature of our planetary system, thus pushing it away.
‘Oumuamua is now passing through the Kuiper Belt, a ring of icy objects near the outer edge of the Solar System, beyond the orbit of Neptune. Not only is it beyond the reach of our telescopes, but the interstellar intruder will never return to Earth or the Sun.
But ‘Oumuamua isn’t the only interstellar intruder we’ve seen enter the Solar System. Comet 2I/Borisov (2I/Borisov) was the second confirmed interstellar object found within the Solar System and the first confirmed interstellar comet.
2I/Borisov was discovered by Crimean amateur astronomer Gennady Borisov on August 30, 2019. This solar system invader truly put A117uUD’s speed to shame, racing through the solar system at a hair-raising 110,000 mph. That’s 150 times the speed of sound and 75 times the top speed of a jet fighter, leaving a Lockheed Martin F-16 in its trail of dust.
RELATED STORIES:
— See every comet photo (and more) from Europe’s Rosetta probe
— Comet Impacts May Have Started Life on Earth
— Comet Variation Could Make Life Common in the Milky Way
Like ‘Oumuamua, 2I/Borisov was merely passing through, briefly captivating both astronomers and the public as it headed toward a solar system exit, never to return.
The encounter between A117uUD and Saturn affected the comet’s orbit so much that the team was unable to reconstruct it before the encounter, but they did what was necessary to ensure that it was not a third extrasolar foreign object.
Perhaps one day, comet A117uUD, launched from Saturn, will excite and captivate astronomers from a distant alien civilization, billions of years after its Earth-based discoverers have disappeared.