Australia's biggest city, Sydney, has switched off its lights for an hour as the Earth Day climate change protest gets under way across the globe.

BBC: Sydney dims down for Earth Hour climate change protest

When companies such as Facebook, Google, YouTube and Twitter started off, were the founders aware from day one that they may change the world?

FORBES: By all means.

However, in one-day internationals a mandatory ball change is now enforced after 34 overs because the white titanium dioxide dye rubs off the leather.

BBC: Pink balls set for one-day trials