Robert Krulwich

Look at this map, and notice that deep, deep in the Republican South, there's a thin blue band stretching from the Carolinas through Georgia, Alabama and Mississippi. These are the counties that went for Obama in the last election. A blue crescent in a sea of red.

You are 200 miles directly above the Martian surface — looking down. This image was taken by the Mars Reconnaissance Orbiter on Jan. 27, 2010. (The color was added later.) What do we see? Well, sand, mostly. As you scroll down, there's a ridge crossing through the image, then a plain, then dunes, but keep looking. You will notice, when you get to the dunes, there are little black flecks dotting the ridges, mostly on the sunny side, like sunbathing spiders sitting in rows. Can you see them?

There was a time — and it wasn't that long ago — when kids would leave home on a summer morning and roam free. "I knew kids who were pushed out the door at eight in the morning," writes Bill Bryson of his childhood in the 1950s, "and not allowed back until five unless they were on fire or actively bleeding." That's what kids did. They went out. Parents let them, and everybody did it. "If you stood on any corner with a bike — any corner anywhere — more than a hundred children, many of whom you had never seen before, would appear and ask you where you were going," Bryson writes.

Before we go slow, let's go fast, so fast you can't go any faster. That would be light in a vacuum, traveling at 670 million miles per hour ...

Light, of course, can slow down. When light passes through water, it loses speed. A diamond is an even better speed bump. It can slow a beam of light by 40 percent.

But moving on, you and I are going pretty fast right now, though we don't notice. The planet we're on is zipping around the sun at 66,000-plus miles per hour ...

So you're minding your own business when all of a sudden, a nuclear bomb goes off, there's a shock wave, fires all around, general destruction and you, having somehow survived, need a drink. What can you do? There is no running water, not where you are. But there is a convenience store. It's been crushed by the shock wave, but there are still bottles of beer, Coke and diet soda intact on the floor.

So you wonder: Can I grab one of those beers and gulp it down? Or is it too radioactive? And what about taste? If I drink it, will it taste OK?