Earth Hour is a global action against climate change.
It started in Australia in 2007 and it has grown to a global day of action. Last year 135 countries across every continent took part.
Organisers hope this year will be even more successful.
More top news
The working poor and elderly fear they will be clobbered when the Chancellor announces his Autumn Statement tomorrow, Penny Marshall writes.
Computer giant Dell apologises for hacking vulnerability and releases instructions on how to remove the rogue eDellRoot Certificate.
Douglas McTavish believes a faulty tumble dryer may be to blame for his 39-year-old son's death in a flat fire last year.