An asteroid might have flipped Ganymede

Four billion years ago, Jupiter’s moon Ganymede might have been permanently turned by an asteroid 20 times bigger than the one that killed the dinosaurs. Researchers analysed distinctive furrows on the moon’s surface that point almost directly away from the gas giant. The furrows could be the remnants of a crater formed by an asteroid that was around 300 kilometres wide, say scientists. The impact might have turned Ganymede’s face away from Jupiter and reoriented its former far side towards the planet.