Make a date tonight with your partner to gaze at the stars or go for a cozy evening with a quiet candle-light dinner.

Or, if you have been postponing that question to your sweetheart, do it in the dark, as you join an estimated one billion people worldwide who will turn off their lights to mark "Earth Hour", from 8:30-9:30 pm.

You will also be keeping celebrity company with Chinese actress Li Bingbing, being chosen by the World Wide Fund for Nature to be the face of Earth Hour on the Chinese mainland.