Tomorrow night millions of people around the world will take a stand against climate change by performing the simplest action—turning off their lights for one hour. The time is here again—it’s the fourth annual Earth Hour!

The World Wildlife Fund created Earth Hour to raise awareness about climate change and convey that, by working together, we can make a difference. Last year’s Earth Hour event involved almost 1 billion people in 87 countries. Even some of America’s most iconic, power-sucking landmarks, from the Empire State Building in New York City to the Las Vegas Strip, participated in the event last year.

It’s easy to participate. Just flip your lights off from 8:30 to 9:30 p.m. in your time zone. Light some candles and enjoy the simple pleasures: a quiet evening with your family and friends, a candlelit block party or a relaxing soak in the tub. Go star gazing—with less lighting in your neighborhood, you’ll be able to see the stars better!

How will you participate this year? Share your stories with us!