How long has it been since you've seen the Milky Way?

I haven't in over 20 years, living inside a moderate-sized city full of light. And that's sad. Will our children even be able to see it in their lifetimes?

Earth Hour: Protecting the Night Sky from Light Pollution

It's a question that many people who popularize astronomy get asked time and again: "How many stars are there?" And while the sky is packed with a myriad of stars, the number visible to skywatchers depends greatly on the local night sky and the impact of city lights.

With Earth Hour 2011 set for 8:30 p.m. local time on Saturday (March 26), now is an opportune time to take a look at the impact of light pollution on the night sky. Earth Hour is a movement that encourages the public to switch off their lights for one hour to conserve power and take a stand against climate change.

(NASA image of light use around the world.)