This is partly due to pollution, but even in the cleanest air the sky is lighter near the horizon due to the effect of earth's atmosphere on sunlight.
Why is the moon sometimes orange or red? Why is the sky blue? These questions are closely related!
You are exposed to relatively high doses of radiation from the time you go through security to the moment your plane lands.
Scientists have found aerosol particles that would have dominated the Earth's pre-industrial atmosphere.
The study of nitrogen compounds found in Titan's atmosphere may help scientists understand how life originally formed on our own planet.
Scared to even look at your electricity bill? Learn how to cut costs on this Moment of Science.
Some clouds appear light and fluffy. Others dark and menacing. But are all clouds made of bacteria?
Could jet streams be a new energy source to power the world's electricity? Find out on this Moment of Science.
Could coal, a carbon-rich fuel, be the key to fixing America's rising gas prices?
Looking for a seaside vacation spot? Consider Saturn's largest moon, Titan. There's no chance of getting sunburned, but you'll want to take a heavy parka...