<p><strong>Silhouetted against still bright city lights below, Rio de Janeiro's "Christ the Redeemer" statue goes dark for <a href="http://www.earthhour.org/Homepage.aspx">Earth Hour 2011</a> on Saturday night. </strong></p><p><strong>The Brazilian icon joined the Empire State Building, the Eiffel Tower, Beijing's Forbidden City, and hundreds of other world landmarks that were abruptly blacked out from 8:30 to 9:30 p.m., local time.</strong></p><p>(See before-and-after<a href="http://news.nationalgeographic.com/news/earth-hour-before-after-2008-2009-pictures/"> Earth Hour pictures</a> from past years.)</p><p>The organizers behind the fifth annual Earth Hour urged people to turn off lights and other nonessential appliances in a symbolic show of support for action against climate change and for energy conservation in general.</p><p>In 2010, 128 countries and territories<a href="http://news.nationalgeographic.com/news/2010/03/100326-earth-hour-2010-record-landmarks/"> took part in Earth Hour</a>. Eighty-nine national capitals participated, as did nine of the world's ten biggest cities, thousands of other communities, countless businesses, and hundreds of millions of individuals, according to<a href="http://www.wwf.org/"> WWF</a>, the international conservation nonprofit that organizes Earth Hour.</p><p>Earth Hour 2011 was even larger, said organizers, who called Earth Hour 2011 "a record breaking year for the annual lights-out event."</p><p>(Related:<a href="http://blogs.nationalgeographic.com/blogs/news/breakingorbit/2010/03/this-earth-hour-dont-forget-to.html"> "This Earth Hour, Don't Forget to Look Up."</a>)</p><p><em>—With reporting by Brian Handwerk</em></p>

Rio During Earth Hour

Silhouetted against still bright city lights below, Rio de Janeiro's "Christ the Redeemer" statue goes dark for Earth Hour 2011 on Saturday night.

The Brazilian icon joined the Empire State Building, the Eiffel Tower, Beijing's Forbidden City, and hundreds of other world landmarks that were abruptly blacked out from 8:30 to 9:30 p.m., local time.

(See before-and-after Earth Hour pictures from past years.)

The organizers behind the fifth annual Earth Hour urged people to turn off lights and other nonessential appliances in a symbolic show of support for action against climate change and for energy conservation in general.

In 2010, 128 countries and territories took part in Earth Hour. Eighty-nine national capitals participated, as did nine of the world's ten biggest cities, thousands of other communities, countless businesses, and hundreds of millions of individuals, according to WWF, the international conservation nonprofit that organizes Earth Hour.

Earth Hour 2011 was even larger, said organizers, who called Earth Hour 2011 "a record breaking year for the annual lights-out event."

(Related: "This Earth Hour, Don't Forget to Look Up.")

—With reporting by Brian Handwerk

Photograph by Felipe Dana, AP

Earth Hour Pictures: Before and After, Around the World

See what it looked like Saturday night when hundreds of landmarks went dark—and cities went darkish—in the name of energy conservation.

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