Camels are just very efficient at using water. If camels' humps are not full of water, why do camels have humps? And where do camels store water?

The answer is ... we don't. But astronomers make educated guesses about the shape of our galaxy, in part by looking into space at other galaxies.

If you any warm object and expose it to cold air, that object will lose heat to the air. Wind chill refers to greater heat loss due to the motion of the air.

Christopher Flavin said over 40 percent of the new generating capacity added in the U.S. last year is from wind power. It's surpassed a little by natural gas.

Economist James Hughes talks about a New Jersey ballot measure that would would offer $400 million in bonds to support land and historic preservation efforts in New Jersey. Dr. Hughes explains why land conservation is profitable for states, and becoming more so.

"Dust is something that travels very far, from one continent to the next across the oceans. The vantage point of space gives you a perspective that you can't see from the ground," says Lorraine Remer.

"We have pollution, we have massive changes to the rivers caused by dams, we alter our lakes and rivers to accommodate cities and farms," says Peter Moyle.

Jeffrey Sachs, is concerned that in the future, the demands of the human population will outstrip the Earth's ability to provide food.

Serge Wich, a scientist at the Great Ape Trust of Iowa, thinks orangutan whistling could provide clues about the evolution of human speech.

The Heene hoax shows us humans tend to favor initial impressions. If the first impression you get of something is that it is an alien spacecraft, it sticks.