The astronomical juxtaposition couldn't be any more stark: in the series of observations above, Jupiter's icy moon Europa passes in front of Io, fellow Jovian moon, but also the most volcanically active place in the entire solar system.
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Imaged by the huge Large Binocular Telescope (LBT), located in the Pinaleno Mountains, Ariz., this Jovian occultation on March 7 serves as a reminder as to the complex assortment of moons our solar system possesses.
On the one hand, we have an ice-encrusted Europa that has a sub-surface ocean with huge habitable potential for exo-marine life. But on the other, there's a magma-covered Io convulsing with powerful volcanic eruptions. Though their differences are obvious, Europa's habitable potential and Io's volcanoes are driven by the same force: the tides of Jupiter.
As the closest Galilean moon in the Jupiter system with an eccentric orbit, Io bears the brunt of Jupiter's tides, suffering huge tidal stresses as it travels around the massive gas giant. This creates an internal dynamo that keeps the 1,942 mile (3,636 kilometer) wide moon in a constantly-erupting state - the stress often becomes too great and huge explosions eject magma from the splitting crust. Orbiting further away, Europa (that is slightly smaller than Io with a diameter of 1,950 miles) also feels these tides, but the impact is far less dramatic.
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Below the thick ice crust is an ocean that is kept in a liquid state by Jupiter's tides compressing Europa's core. But rather than generating the pressure-cooker that is Io, Europa has an internal heater that generates enough heat to keep its underground ocean liquid.
Loki, the Fire God Now, by using the LBT's twin 8.4 meter (27 feet) telescopes working in unison, never before seen features on Io's surface pop into view.
A pooling, vast lake of magma is known to exist on Io, covering a region 124 miles wide. This feature, called "Loki" after the Norse god of fire and chaos, is known as a patera where a cooling lava crust floats atop molten rock. Periodically, the upper layers submerge into the magma, generating a surge in thermal emissions that can be observed from Earth.
Observing Io with the Large Binocular Telescope Interferometer, or LBTI, in infrared light, features in the Loki Patera have become easier to study.
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