Millions of people across the world will celebrate Earth Hour 2013 on Saturday, March 23 at 8:30 p.m. to 9:30 p.m. local time. This global movement by the World Wildlife Fund (WWF) is not just a lights out event, but something beyond to protect this planet. To celebrate Earth Hour, here is a beautiful video by the South Africa based multimedia company Earth Touch. Switch off your lights, close your eyes and listen the sounds of the nature. Which animal species can you hear?