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Discover the colossal impact: Asteroid 20 times larger than the one that destroyed the dinosaurs caused profound changes to the largest moon in the Solar System
Approximately 4 billion years ago, an asteroid of colossal proportions collided with Ganymede, Jupiter's largest moon, generating an impact so powerful that it significantly altered its axis of rotation.
According to a study led by Hirata Naoyuki of Kobe University in Japan, this event drastically reshaped the moon's surface, resulting in changes that are still visible today.
Ganymede: The Giant of the Solar System
Ganymede, the largest moon of Jupiter and the Solar System, is larger than even the planet Mercury. Like Earth's Moon, Ganymede also always presents the same face to Jupiter, while the other part of its surface remains "hidden" from our eyes. Its surface, marked by craters that form concentric circles, has raised suspicions of a catastrophic impact since the 1980s.
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Researchers speculated that these patterns were due to a collision with a giant asteroid, but the true extent of this impact and its effects on Ganymede remained unknown for a long time. Now, thanks to Hirata's observations and detailed analysis, we finally have a clearer understanding of what happened.
The discovery of impact
Hirata's interest was piqued when he noticed similarities between the craters on Ganymede and a crater on Pluto, which was also caused by an impact that altered the dwarf planet's axis. This finding led him to consider that Ganymede might have experienced a similar phenomenon.
The study, published in the journal Scientific Reports, reveals that the asteroid that collided with Ganymede was about 150 kilometers in diameter, an imposing mass compared to the asteroid that caused the extinction of the dinosaurs on Earth, estimated at 10 to 15 kilometers in diameter. By hitting Jupiter's moon at a speed of 20 kilometers per second, the impact caused a massive redistribution of material, changing Ganymede's axis of rotation and creating the concentric scars we see today.
Although Ganymede has been known since 1610, when Galileo Galilei first observed it with his telescope, the Jovian moon still hides many secrets. It was only with the arrival of the Voyager probes that scientists were able to closely observe its craters, grooves and other geological features. Ganymede's surface is marked by long grooves and ridges that intrigue scientists. astronomers until today.
These grooves, which cover a significant portion of the moon, are traces of its turbulent past and major collisions. Through computer simulations, Hirata and his team were able to determine that the impact 4 billion years ago was so powerful that it caused a reorientation of Ganymede's axis.
Impact changed the Solar System
The Solar System, especially during its formation, was the scene of countless catastrophic impacts that shaped its planets and satellites. Uranus, for example, may have been hit by a large runaway moon, altering its tilt. Earth's own moon is the result of a large impact that reshaped the planet. Pluto, in turn, had its shape influenced by the tidal forces of its satellite, Charon.
In the case of Ganymede, Jupiter’s gravity plays a crucial role, forcing the moon to always keep the same face toward the planet. Ganymede’s concentric grooves align with an area directly opposite Jupiter, as if the moon were “staring” into space, away from its giant host.
Hirata’s research sheds light on the colossal impact that reshaped Ganymede and opens new perspectives for the study of the Jovian moons. Planetary models indicate that after the impact, rocks and ice ejected by the collision fell back onto the surface, altering its mass distribution and forcing a reorientation of the moon’s axis.
However, many open questions remain. For example, how did the impact affect Ganymede's internal structure? How do the liquid oceans believed to exist beneath its crust influence the moon's mass distribution and geological activity?
Future research
Future research promises to delve deeper into these mysteries, using more detailed data from Jupiter's icy moons to better understand the complex evolution of Ganymede and other satellites in the Solar System.
The colossal impact that struck Ganymede billions of years ago not only left permanent marks on its surface, but also altered its axis of rotation. Studies like Hirata’s continue to unravel the mysteries of the Solar System, giving us a clearer picture of how these catastrophic events shaped the celestial bodies we know today.
Ganymede, despite being one of Jupiter's best-known moons, still holds deep secrets that could change the way we understand the formation and evolution of the moons and planets around us.
