The Cracks On Ganymede Were Considered The Largest Impact Structure In The Solar System
Cracks on Ganymede, Jupiter's largest moon, may have remained after it collided with another large celestial body, according to the journal Icarus. If the hypothesis of scientists is correct, then the observed traces can be considered the largest impact structure, known today.
Ganymede is the largest satellite in the solar system and the ninth-largest object in It, which is larger than even mercury. Its diameter is 5.2 thousand kilometers, and its mass is about twice the mass of the moon. Studies of Ganymede using various space stations, including Voyager 1, Voyager 2, and Galileo, have shown that its surface is covered with concentric furrows, each several kilometers wide. Astronomers speculated that the cracks could have been caused by the moon colliding with another celestial body, but the force and scale of the event were still unclear.
Naoyuki Hirata from Kobe University, along with colleagues, re-analyzed images taken by past missions and found that the cracks on Ganymede are larger than previously thought. According to their estimates, the length of the furrows is about 16 thousand kilometers — that is, they almost completely encircle the surface of the Jovian moon. A simulation built by astronomers showed that the cracks could have appeared as a result of the collision of Ganymede with another celestial body with a diameter of 300 kilometers. If this is true, then the tracks on Jupiter's moon are the largest impact structure in the Solar system, larger even than the 2,500-kilometer-long South pole-Aitken basin: according to scientists, it appeared after the fall of a 200-kilometer asteroid.
The authors suggest that an unknown celestial body fell on Ganymede about four billion years ago in an area known as the Marius region. Since then, the satellite's surface has changed significantly due to volcanism and tectonic activity, which has erased some traces from the surface. However, the furrows remain in older and darker areas, which cover about a third of the surface, and so astronomers see the cracks left by the collision, but not the impact crater itself.
The fall of the asteroid must have had a major impact on the Geology and internal evolution of Ganymede. Therefore, data obtained during future missions, such as JUICE or Europa Clipper, will allow us to verify the authors' conclusions.
Earlier, scientists found that Ganymede, along with another moon, IO, leaves impressions on the Aurora, which is observed at the poles of Jupiter.