Europa, one of Jupiter's 64 known moons, has been one of the prime candidates for possible life outside of planet Earth since it was first observed up close in the 1990s. Covered almost entirely in ice, scientists believed that in all likelihood vast oceans exist deep below the ice, which may just be warm enough to support aquatic organisms.
New research suggests that Europa may not just have a gigantic ocean under its icy surface, however - it may have lakes closer to the surface as well, which ups the possibility that life in some form could exist on Europa, whether it's in the lakes or the world-spanning oceans.
But how do lakes, not to mention a massive ocean, exist on a planet that is roughly 485,000,000 miles away from the Sun? As it turns out, Europa has an extremely active core thanks to its close proximity to Jupiter. Jupiter's constant tugging on Europa kicks the moon's core into overdrive, which then heats the planet enough to be able to sustain liquid water.
The lakes, on the other hand, likely don't stay in liquid from permanently. It's believed that the lakes freeze and unfreeze over the course of several hundred, if not several thousand, years due to periodic transfers of energy from the moon's core to the surface.
[Image credit: NASA/Ted Stryk]