Earth Hour

Earth Hour, celebrated every March 28 from 8:30-9:30 pm local time, is a worldwide grassroots movement uniting people to protect the planet, and is organized by World Wildlife Fund. Engaging a massive mainstream community on a broad range of environmental issues, Earth Hour was famously started as a lights-off event in Sydney, Australia in 2007. Since then it has grown to engage more than 7,000 cities and towns worldwide, and the one-hour event continues to remain the key driver of the now larger movement.

https://www.earthhour.org/