Enormous asteroid affect might have knocked over Jupiter’s largest moon

An enormous collision billions of years in the past might have dramatically reoriented Ganymede, Jupiter’s largest moon.

Naoyuki Hirata at Kobe College, Japan, and his colleagues studied Ganymede’s intensive furrow system, a collection of concentric troughs believed to be remnants of the biggest affect construction within the outer photo voltaic system.

The centre of the furrow system aligns carefully with Ganymede’s tidal axis – the imaginary line working to Jupiter from the centre of the moon’s aspect that all the time faces its planet. This led the researchers to recommend that the affect that shaped the furrows brought on a big redistribution of mass that reoriented the moon.

Via simulations, the researchers decided that the impactor accountable in all probability had a diameter of about 150 kilometres ­– considerably bigger than the one which brought on the extinction of the dinosaurs on Earth, which is estimated to have had a diameter of about 10 kilometres.

Andrew Dombard on the College of Illinois Chicago says that if an asteroid like that hit Earth, “it would be a global sterilising event, a bad day”.

Upon affect, this asteroid would have breached Ganymede’s icy crust into the liquid oceans under, making a transient crater and hurling huge quantities of fabric throughout the moon’s floor.

As this settled, it might have shaped a thick blanket of ejecta across the affect web site, making a area the place gravity is stronger as a result of additional mass. Over time, this anomaly would trigger Ganymede to reorient, aligning the affect web site with its tidal axis, the simulation confirmed.

Hirata’s staff in contrast this course of with an occasion on Pluto, the place a big affect created a basin known as Sputnik Planitia, resulting in a reorientation of the dwarf planet.

Nonetheless, though it’s doubtless that the Ganymede affect considerably affected the moon’s early historical past, estimating the scale of the item that hit it’s sophisticated as a result of we lack good knowledge on the gravity and topography of this frigid world, says Hirata.

Dombard says the mannequin used within the paper doesn’t account for a few of the complexities of Ganymede’s distinctive icy construction. “I think it is very good for establishing that this process could occur, but I don’t necessarily trust the numbers,” he says.