The effects of relative proximity between these large moons seem to have been underrated. Not forgetting that Jupiter does have a big effect on Io, the closest Galilean moon to it.
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Jupiter’s “ocean world” moons may have strong gravitational effects on each other, raising big tides in each others’ subsurface seas, a new study suggests [Space.com reporting].
Surprisingly, these moon-moon tidal forces might generate more heat in the satellites’ oceans than the gravitational tugs of giant Jupiter, study team members found.
“That’s kind of interesting, because Jupiter is the biggest mass in that system, so its tidal forces are much bigger than one moon on another,” lead author Hamish Hay, who performed the work while at the University of Arizona’s Lunar and Planetary Laboratory, said in a statement.
Hay and his colleagues modeled the gravitational interactions among Jupiter’s four large Galilean moons — Io, Europa, Callisto and Ganymede.
The latter three are thought to harbor huge oceans of liquid water beneath their icy shells, whereas powerfully volcanic Io might have a subsurface sea of molten rock.
The researchers determined that the Galilean moons have an outsized influence on each other thanks to “tidal resonance” — basically, a reinforcing sync-up of a gravitational tug and the natural rocking of the satellites’ oceans.
The moons are more tidally resonant with each other than with Jupiter, which explains why the giant planet’s powerful pull doesn’t translate into bigger tidal effects.
As an example: Hay and his team calculated that Jupiter’s tug could generate a tidal wave in Europa’s buried ocean if that sea were about 660 feet (200 meters) deep.
Little Io, by contrast, could get a strong wave going in a Europan ocean 50 miles (80 kilometers) deep.
Full article here.
Related Talkshop post: Why Phi? – the resonance of Jupiter’s Galilean moons
via Tallbloke’s Talkshop
August 28, 2020 at 12:54PM