Scientists are fairly confident that Jupiter’s moon Europa has an underground ocean, even though they’ve never seen it.
Hidden beneath an icy crust, most of what researchers know about that ocean is based on the moon’s smooth, streaked surface. Europa lacks mountains or large craters, but it is crisscrossed with ridges and cracks, called chaos terrain, that scientists think is caused by the shifting of ice plates over a liquid ocean, analogous to Earth’s plate tectonics.
By using the Hubble Space Telescope to spy on Europa’s surface, astronomers have discovered the presence of sodium chloride – better known as table salt, the same compound that makes Earth’s oceans so salty. This might indicate that Europa’s ocean is more like Earth’s or Enceladus’ oceans than previously thought, and bolsters some theories about hydrothermal activity on the moon.
The only spacecraft to visit Jupiter’s moons up close was Galileo, back in the ...
