On Jupiter’s moon Io, a huge lava-filled basin is home to dual tidal waves that regularly sweep across its surface.

The Loki Patera is a lake of molten rock some 8,300 square miles in size with a large island in the center, first imaged by the Voyager spacecraft that flew by Jupiter in 1979. Periodic swings in brightness, imaged both by spacecraft and Earth-based telescopes indicated that something was disturbing the surface on a semi-uniform basis.
Pulled In Different Directions
Io is