Several years ago I talked The Sun into sending me out to Nebraska to do a story on people who travel far to see the stars. I flew out to Omaha and drove to Valentine, in the Sand Hills region of north-central Nebraska, to attend the Nebraska Star Party - a gathering of amateur astronomers under one of the darkest skies on the continent.

While there, I fell in love with the Sand Hills. It's place of rolling grasslands and vast cattle ranches, watered by springs and lakes that bubble up from the underlying sands and the Ogallala Aquifer beneath. The hills, it turns out, are actually sand dunes. Until about a thousand years ago the place was a Sahara-like desert, and the dunes were on the move. It was a barren wasteland, and could become one again if the rains quit.

The Sand Hills depend on spring and summer rainfall that pushes north and west from the Gulf of Mexico. It's not abundant rain, but it's enough to keep the grass growing and the cattle (and before them the buffalo) fed. Not surprisingly, scientists at the University of Nebraska have been studying the state's climate for many years, trying to understand why the rains stopped and turned their land into shifting sand, and whether it might happen again.

Here's a release from the university describing the latest findings by their researchers, who say it was a shift in the prevailing winds a thousand years ago - perhaps linked to climate change in Medieval Europe - that turned on the rains from the Gulf and began watering - and stabilizing - the Sand Hills. What they don't know yet is what it would take to turn the rains off again, an event that would choke the economic life from the region.