Earth Hour asks individuals and businesses to turn off their lights at 8:30 p.m. on April 30, in an effort to raise awareness about climate change. The Sydney Opera House , Empire State Building and Eiffel Tower will go black . Organizers have pledges from 147 countries and over 5,000 cities to go dark . In Dubai , the world 's tallest building , the Burj Khalifa , will switch off its lights . An astronaut on the International Space Station will blog on event from orbit .
Earth Hour asks individuals and businesses to turn off their lights at 8:30 p.m. on April 30, in an effort to raise awareness about climate change. The Sydney Opera House , Empire State Building and Eiffel Tower will go black . Organizers have pledges from 147 countries and over 5,000 cities to go dark . An astronaut on the International Space Station will blog on event from orbit .