By | March 22 2013 5:48 AM

At 8:30 p.m. this Saturday the Sydney Opera House will go dark. Soon after, the Great Wall of China, the Burj Khalifa, the Eiffel Tower, Christ the Redeemer, the Empire State Building and countless others will follow suit. But if you notice any partial blackouts this weekend, fear not. The symbolic gesture simply marks each nation’s commitment to sustainability in 2013 in honor of Earth Hour.