Saturn's first Trojan asteroid has been discovered at last.

"Astronomers have finally discovered an asteroid that shares Saturn's orbit around the sun. These types of objects, known as Trojan asteroids, were previously known to exist around the other three giant planets.

'Saturn was sort of the odd man out, if I can call it that, because even though it’s the second most massive planet in the solar system, it had no Trojans,' says Paul Wiegert, an astronomer at the University of Western Ontario in London, Canada. Like Saturn, the newly found asteroid takes about 30 years to complete an orbit but stays 60 degrees ahead of the planet, according to research submitted by Wiegert and his colleagues on September 29 to arXiv.org."

"Most asteroids in the solar system orbit the sun between Mars and Jupiter. However, in 1906, German astronomer Max Wolf discovered the first Trojan asteroid, named Achilles, which orbits the sun 60 degrees ahead of Jupiter. Since then, thousands of additional Trojan asteroids have been identified—some leading Jupiter by 60 degrees, others trailing by the same distance. NASA's Lucy spacecraft is set to visit eight of these asteroids between 2027 and 2033 (SN: 10/15/21).

Trojan asteroids have also been found around Uranus, Neptune, Earth, and Mars (SN: 2/1/22).

After a telescope in Hawaii captured an image of a new asteroid in 2019, Australian amateur astronomer Andrew Walker proposed that it might be a Saturnian Trojan—if it followed the right orbit around the sun."

'The key to determining a precise orbit for an object in our solar system is having numerous observations from different telescopes over an extended period,' says Wiegert. To achieve this, astronomer Man-To Hui at Macau University of Science and Technology in China searched for past images of the asteroid and planned new observations. Data on the asteroid's position, spanning from 2015 to 2024, confirmed its status as a Trojan. Named 2019 UO14, the asteroid is about 13 kilometers wide, roughly the same size as Deimos, Mars's smaller moon.

Scientists have long anticipated the existence of Saturnian Trojans, says astronomer Carlos de la Fuente Marcos of Complutense University of Madrid, who was not involved in the discovery. However, he notes that all Saturnian Trojans are expected to have unstable orbits, due to the presence of giant planets on either side of Saturn.

"'Jupiter seems to be the culprit,' de la Fuente Marcos says. The immense gravity of Jupiter gradually tugs on a Saturnian Trojan, causing its orbit around the sun to become more elliptical. Eventually, the asteroid drifts close enough to Jupiter or Uranus that one of these giant planets pulls it out of its Trojan orbit.

The researchers estimate that the asteroid has only been a Trojan for about 2,000 years and will remain in this state for roughly another 1,000 years. Before its interaction with Saturn, the asteroid was likely a centaur—an object orbiting the sun among the orbits of the giant planets (SN: 11/12/77).

This asteroid is probably not Saturn’s only Trojan. 'I’m quite sure there are more—maybe only a few, but this can’t be the only one,' Wiegert says."

Get traffic for your website