Researchers from Kobe University have identified what may be the largest impact crater in the Solar System on Ganymede, Jupiter's largest moon. Simulations suggest it was formed by a 150-km-radius asteroid striking at 20 km/s, creating a ring of furrows with a 7,800-km radius.
Ganymede, Jupiter's largest moon and the Solar System's biggest natural satellite—with a diameter 8% larger than Mercury—features prominent furrows observed by NASA's Voyager probes in the late 1970s and Galileo mission around 2003. As detailed in a SciTechDaily article from August 7, 2020, Kobe University scientists reanalyzed these features, with findings set for publication in the journal Icarus in December 2020.
By mapping the orientation and distribution of these furrows across Ganymede's surface, the team determined they represent the remnants of a massive impact crater. These grooves, among the moon's oldest surface features, offer key insights into its geological history.
The furrows form a ring pattern spanning approximately 7,800 km in radius. Using the "PC Cluster" supercomputer at Japan's National Astronomical Observatory, simulations confirmed the crater resulted from a 150-km-radius asteroid impacting at 20 km/s about 4 billion years ago.
This discovery points to the Solar System's largest known impact crater—four times bigger than Jupiter's Callisto's Valhalla crater, which has a 1,900-km radius.
The impact likely delivered the immense heat needed to shape Ganymede's unique internal structure. Future missions could verify these findings and deepen our understanding of the moon's evolution.
