Impactful Events

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The asteroid that struck Earth about 66 million years ago caused a cataclysmic event that wiped out the dinosaurs.

But that was probably just a drop in the ocean compared with what happened to one of Jupiter’s moons, Ganymede.

A new study recently found that the asteroid strike on Ganymede – also the largest moon in the Solar System – was so massive it caused the moon’s axis to shift.

Ganymede is known for its icy surface and hidden oceans. However, its surface also bears visible scars from the ancient impact: Researchers have long puzzled over the furrows – concentric grooves that stretch across large parts of the moon’s surface – suspecting they were the result of a massive asteroid collision, reported Science Alert.

Study author and planetary scientist Naoyuki Hirata from Japan’s Kobe University concluded that the asteroid responsible for Ganymede’s furrows was about 185 miles wide – about 20 times larger than the one that hit Earth.

“We know that this feature was created by an asteroid impact about 4 billion years ago, but we were unsure how big this impact was and what effect it had on the moon,” Hirata explained in a statement.

Hirata’s computer simulations showed that the asteroid created an 870- to 1,000-mile wide transient crater, an enormous scar that likely wiped away Ganymede’s original surface. The simulations also confirmed that the impact would have drastically affected the moon’s internal structure and potentially altered its subsurface oceans.

The study also suggests that the asteroid strike was powerful enough to shift Ganymede’s rotational axis. This is evidenced by the furrows now lying almost exactly opposite Jupiter – a change in orientation caused by the redistribution of mass after the impact.

Ganymede’s impact remains an important collision event in the Solar System’s history because it offers researchers insights into how such asteroid strikes shape the surfaces, interiors, and rotational dynamics of celestial bodies.

The European Space Agency’s JUICE probe, set to arrive at Ganymede in 2034, will provide further insights into this ancient event, according to the Guardian.

“I believe that further research applying the internal evolution of ice moons could be carried out next,” Hirata said, noting that the probe’s data will help answer lingering questions about Ganymede’s evolution.