The most gigantic impact crater in our solar system may reside on Jupiter’s moon Ganymede. It’s not surprising that the 4.5 billion-year-old Ganymede would be full of impact craters as it isn’t just Jupiter’s largest moon but it’s also the biggest satellite in our entire solar system. For comparison, it is bigger than Mercury and Pluto, and three-quarters the size of Mars. As a matter of fact, if Ganymede was orbiting the sun instead of Jupiter, it would have been classified as a planet instead of a moon.
In previous research, scientists found a bunch of features called furrows which indicate that a huge impact occurred on Ganymede that left a number of scars across one full side of the moon. The giant impact created a bunch of rings and fractures that then turned into troughs and furrows. However, with a new study recently conducted, scientists now believe that the impact was so massive that it affected the entire moon.
Scientists analyzed information that was collected by NASA’s twin Voyager missions, and the Galileo mission, as well as data from observations on the Dark Terrain of the moon where the oldest surfaces on Ganymede are located. They found that all of the furrows – even the ones on the opposite side of the moon – rippled out from one location which strongly suggests that it was one giant impact that affected the whole moon.
If their analysis is correct, that means that Ganymede holds the largest impact crater in our solar system with a radius as massive as 4,800 miles. This would smash the current record that another one of Jupiter’s moons holds. Callisto currently has the largest impact crater (called Valhalla Crater) that has a radius of 1,200 miles. Interestingly, Callisto is Jupiter’s second largest moon – second to Ganymede.
So, how large was this asteroid that possibly affected the entire moon? Scientists believe that it would have been at least 30 miles across and potentially even larger than 90 miles across.
Since a bunch of rings/furrows isn’t enough to pinpoint an exact location of the impact site, a lot more work needs to be done. Hopefully the European Space Agency’s JUpiter ICy moons Explorer (or JUICE) will help answer that very question when it is launched into space in 2022. It will arrive at Jupiter in 2029 and remain there for at least three years to gather data from the planet as well as three of its moons – Ganymede, Callisto and Europa.