Lights out.

Tonight, you millions of people and hundreds of communities in 135 countries around the world by switching off all non-essential lights for an hour beginning at 8:30 p.m. as part of Earth Hour.

The Sydney Opera House and Harbour Bridge, The Tokyo Tower, the Bosphorus Bridge in Istanbul, the Kremlin and Red Square in Moscow, the statue of David in Florence, The Eiffel Tower, Berlin's Brandenburg Gate, The Little Mermaid statue in Copenhagen, The Houses of Parliament, Buckingham Palace and The Empire State Building are some of the worldwide landmarks which will be going dark Saturday.

While the symbolism of a dark world without sustainable resources is one aspect of the campaign, Earth Hour aims to encourage "an interconnected global community to share the opportunities and challenges of creating a sustainable world," according to co-founder Andy Ridley, the Austrailian who began Earth Hour seven years ago in Sydney.

"Earth Hour asks everyone to take personal accountability for their impact on the planet and make behavioural changes to facilitate a sustainable lifestyle. Taking the first step is as easy as turning off your lights. By switching off your lights for Earth Hour you are acknowledging and celebrating your commitment to do something more for the planet that goes beyond the hour," Ridley said.