According to a study published on Tuesday, September 3, a giant asteroid would have rotated on its axis Ganymede, the largest moon in the solar system belonging to Jupiter.
It narrowly escaped annihilation. The solar system’s largest moon, Ganymede, was struck by an ancient asteroid 20 times larger than the rock that crashed into Earth and ended the reign of the dinosaurs 66 million years ago.
According to a study published this Tuesday, September 3 by Scientific Reports, the devastating impact that Ganymede experienced is not recent. It took place 4 billion years ago and even caused the rotation of the star, one of Jupiter’s moons, so that the impact crater points away from the gas giant.
A giant asteroid
Until now, scientists were unaware of the impact of the asteroid on Ganymede. For a long time, the grooves on the Jovian moon were thought to be the remains of multiple concentric rings created by the impact of a giant asteroid, although the magnitude of the impact was not determined.
But one unusual detail caught the researchers’ attention. The center of the grooves visible on Ganymede points almost directly away from Jupiter. Now, like the Moon and Earth, Ganymede is synchronized with the planet Jupiter, which means that it should constantly show the same face to the gas giant.
If the impact crater is instead facing away from Jupiter, this suggests that the asteroid that hit Ganymede destabilized the star, due to its weight, causing it to spin on itself.
According to computer models, the asteroid was probably 185 miles in diameter and struck at an angle of 60 to 90 degrees. The impact created an initial crater up to 1,000 miles wide, which partially filled in as rock and dust from the collision fell back.
The impact could have had dramatic consequences for Ganymede, which, at more than 5,000 kilometres wide, could have seen “the original surface completely obliterated”, Dr Naoyuki Hirata of Kobe University in Japan told the Guardian newspaper. The impact could have been even more dramatic, with researchers speculating that Ganymede contains a hidden saltwater ocean.
Difficult to make sense of
This is not the first time that craters on stars have intrigued scientists. Leigh Fletcher, a planetary scientist at the University of Leicester, said the ancient terrains of Jupiter’s moons were evidence of billions of years of bombardment, still visible today.
“It’s difficult to make sense of all these overlapping events on the surface of satellites,” he said.
Commenting on the recent study on Ganymede published on Tuesday, Leigh Fletcher believes that “it is an interesting attempt to go back in time through computer simulations”, reports The Guardian.
Launched into space in April 2023, the European space probe Juice is expected to continue exploring Ganymede. Acronym for Jupiter Icy Moons Explorer, Juice has been undergoing multiple trajectory corrections since August 19 to successfully complete its mission to explore Jupiter and its icy moons.
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