This combination picture shows the Serbian National Assembly building in Belgrade before and after submerging into darkness as part of the Earth Hour switch-off on March 23, 2013. Organisers expect hundreds of millions of people across more than 150 countries to turn off their lights for 60 minutes on Saturday night — at 8:30 pm local time — in a symbolic show of support for the planet. While more than 150 countries joined in last year’s event, the movement has spread even further afield this year, with Palestine, Tunisia, Suriname and Rwanda among a host of newcomers pledging to take part. AFP PHOTO / ANDREJ ISAKOVIC