Water, water everywhere, nor any drop to drink.

The line from “The Rime of the Ancient Mariner” is true not only on Earth, but across the solar system. Water is everywhere. But it’s not in a form you could drink. It’s in the clouds of the giant outer planets, frozen in the surfaces and ice caps of planets and moons, or buried far below their surfaces.

One example is Pluto. The dwarf planet is billions of miles from the Sun, so its surface is frozen. But there’s evidence that liquid water lurks far below. In fact, there could be a global ocean up to a hundred miles deep.

One bit of evidence is a feature called Sputnik Planitia – a fairly smooth plain about 600 miles across. It’s almost pure white. And there are no impact craters, suggesting that the surface is young.

Among its features are floating blocks of frozen gases. They resemble slabs of ice in the polar regions of Earth. That suggests they could be floating atop liquid water. Plumes of water flow upward, freezing and pushing older ice outward. In fact, the feature might have formed when a big asteroid slammed into Pluto. It vaporized the surface, exposing the ocean below. The water quickly froze, forming the plain we see today.

Pluto lines up opposite the Sun this week. It’s in view all night, and shines brightest for the whole year.

Script by Damond Benningfield