So what is the "Mars mystery" NASA has solved? Flowing water on the red planet.

This is indeed a major discovery. Where there's water, there may be life. But in this case I wouldn't hold your breath.

NASA hyping this finding is a bit like throwing a party over a patch of wet sand in a desert when — right around the celestial corner — at least two vast, habitable oceans remain unexplored.

The news we heard Monday dates back to 2011, when an undergraduate named Lujendra Ojha discovered dark streaks on the slope of a crater near the Martian equator.

Back then, Ojha, planetary scientist Alfred McEwen, and other researchers announced in the journal Science that these streaks, called "slope lineae," appeared during warmer periods on Mars. (McEwen also led a 2013 follow-up study in the journal Nature.) They suggested that water ice in the soil was melting, leaking down the crater wall, and showing up in Mars Reconnaissance Orbiter satellite images.