There’s no liquid water on the surface of Mars. But if you could squeeze the planet like a damp sponge, a lot of water might ooze out. Observations by a Mars lander suggest that huge amounts of water might lurk below the surface – enough to cover the entire planet with an ocean a mile deep.

Mars was much warmer and wetter in the distant past. Rivers flowed across the surface, feeding into lakes and perhaps a giant ocean. Most of that water has vanished. There’s some frozen water in the polar ice caps and in slabs below the surface, but no liquid water.

Scientists have been trying to figure out what happened to the rest of the water. Some of it was lost to space. But some could have trickled below the surface, in either liquid or frozen form.

The InSight lander listened for “marsquakes” for four years. The way sound rumbles through the planet reveals details about what’s below the surface.

A recent look at those observations suggested there could be a lot of water more than seven miles down. It would be contained in cracks and pores in volcanic rock – not as underground reservoirs. Still, it’s more than enough water to account for the ancient lakes and ocean – now hidden far below the Martian dunes.

Look for Mars close to the upper right of the Moon as they climb into good view in late evening. The planet looks like a bright orange star.

Script by Damond Benningfield