A giant lake of molten rock forms a dark horseshoe on the surface of Io, one of the big moons of Jupiter, in this view from the Galileo spacecraft. Io is the most volcanically active body in the solar system. Loki Patera (just below center) is the largest of its volcanic features — a lake that covers about 7,000 square miles. Fresh lava bubbles up from below to fill its basin. [NASA/JPL]
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Moon and Jupiter
A giant lake spreads across the surface of Io, one of the big moons of Jupiter. You wouldn’t want to take a dip in it, though — it’s a pool of molten rock that sizzles at up to 2,000 degrees Fahrenheit.
Io is about the same size as our own moon. But while the Moon is almost completely dead, Io is the most volcanically active body in the solar system. It’s heated by a gravitational tug-of-war between Jupiter and some of its other big moons. This conflict pulls and twists Io’s interior, melting some of its rock. Some of the molten rock pushes its way to the surface through volcanic mountains and lava lakes.
Loki Patera is the largest of these volcanic features — a lake that covers about 7,000 square miles. Fresh lava bubbles up from below to fill its basin, which is shaped like a horseshoe.
Over time, lava at the top of the lake cools and hardens to form a crust, so Loki Patera fades. But the crust is heavier than the molten rock below it, so it sinks, letting the hot lava rise to the surface.
Loki Patera was especially active through much of 2013. It faded in September of that year, but brightened again in October of last year — indicating that lava was once again bubbling to the surface of this giant hot tub.
And Jupiter is quite close to our own moon tonight. The planet looks like a brilliant star close to the upper left of the Moon at nightfall.
Script by Damond Benningfield, Copyright 2015