Jupiter's moon Ganymede may have shifted on its axis when a massive asteroid slammed into it about 4 billion years ago, according to a new study.
Ganymede, the largest moon in the Solar System, is larger than even Mercury and the dwarf planet Pluto. And previous research has found evidence suggesting that beneath its thick ice crust lies a salty ocean that is 10 times deeper than Earth's oceans.
But many questions remain about the moon, and scientists need more high-resolution images of its surface to unravel the mysteries surrounding Ganymede's history and evolution.
Deep grooves cover large areas of Ganymede's surface and form a pattern of concentric circles around one spot, leading some astronomers to believe the moon experienced a major impact in its past.
"Jupiter's moons Io, Europa, Ganymede and Callisto all have interesting individual features, but the one that caught my attention was these furrows on Ganymede," Naoyuki Hirata, an associate professor of planetology at Kobe University in Japan, said in a statement. "We know this feature was created by an asteroid impact about 4 billion years ago, but we weren't sure how big that impact was and what effect it had on the moon."
Hirata is the author of a new study published in the journal Scientific Reports that examines what created Ganymede's crater system and the impact's aftermath - which could be studied in more detail by the European Space Agency's Juice spacecraft, which in is currently on its way to explore Jupiter and its moons.
Ganymede has long attracted the attention of Hirata, who says he thinks revealing its evolution is "significant." The surface of the moon is a study in contrasts, with bright areas of ridges alongside furrows that intersect darker areas.
Hirata is taking a closer look at Ganymede's system of grooves, which extend from a point on the lunar surface much like the concentric cracks that form when a rock hits a car windshield, he says.
Hirata noticed that the center point of the furrow was along the moon's spin axis, suggesting that something like a large impact had caused the moon to completely shift. | BGNES
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