Prolific Twitterer Chris Hadfield has shared a photo of Christchurch's Earth Hour efforts as viewed from space.
Hadfield, an astronaut with the Canadian Space Agency, tweeted a photo of Christchurch's city centre with light's blazing after Earth Hour had ended.
He wrote: "Christchurch, NZ, taken just after Earth Hour ended. The perfect grid system of the downtown core is clearly visible."
He posted similar photos of San Francisco, Las Vegas, Detroit, Chicago, New York and Baltimore.
Earth Hour, held last night, asks participants to conserve power by switching all lights off between 8.30-9,30pm.
Hadfield has been living aboard the International Space Station since December.