Summary:
- A massive asteroid impact over 4 billion years ago caused Ganymede, Jupiter's largest moon, to roll over on its side.
- The impact was so powerful that it left a huge impact basin on Ganymede's surface, measuring over 600 km (370 miles) in diameter.
- This rollover event likely had a significant impact on Ganymede's internal structure and geology, potentially affecting its potential for hosting life.