Photos: Cities dim for 'Earth Hour'
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Credit: AFP/Getty Images
This combo of pictures shows Buenos Aires' Planetarium with the lights on (top) and with the lights off (bottom) during the annual Earth Hour event on March 31, 2012. Millions of people were expected to switch off their lights for Earth Hour on March 31 in a global effort to raise awareness about climate change that was even to be monitored from space. AFP PHOTO / Alejandro PAGNI (Photo credit should read ALEJANDRO PAGNI/AFP/Getty Images)
