Mars just keeps getting wetter. New studies turn up new sources of water on the planet all the time. Late last year, in fact, geologists reported the discovery of a slab of water ice that’s big enough to fill Lake Superior, the largest of the Great Lakes.

Modern-day Mars is a vast desert — it’s cold and extremely dry. And the air is too thin for any liquid water to exist on the planet’s surface. But Mars was much warmer and wetter in the distant past, with rivers, lakes, and perhaps even a giant ocean. Much of that water has escaped into space, but some remains — most of it in the form of ice, either in the polar caps or buried below the dusty surface.

Geologists at the University of Texas at Austin uncovered some of that ice. They used radar aboard Mars Reconnaissance Orbiter to probe deep below the surface of Utopia Planitia, a vast plain that’s halfway between the equator and the north pole. The radar detected a layer of ice that’s as big as the state of New Mexico, and up to 500 feet thick.

That layer could contain clues about how the Martian climate has changed over the eons. So digging into it might tell us more about why some regions kept their water, while others lost it all.

And Mars is in great view tonight. The Sun’s fourth planet looks like a modest orange star close to the upper right of the Moon this evening. The much brighter planet Venus stands to the lower right of the Moon, shining as the brilliant “evening star.”

Script by Damond Benningfield