2、Earth Hour, an annual international event held on the last Saturday of March, asks people to turn off their lights from 8.30 to 9.30 pm of the local time. Its purpose is to raise people’s awareness of the environmental protection and the climate change. Earth Hour first began in Sydney in 2007 and after that, it spread around the world at an amazing speed. This year, more than 4.000 cities from 90 countries and some one billion people from around the world have joined Earth Hour. Though it is a single mass event, people are contributing in their own way to saving our planet and one hour’s going dark means a bright future.