"What are you doing on July 20? Could you could spare a few moments to help make history? If so, the organisers of World Jump Day would like to hear from you. They believe that if enough people, all over the planet, jump up and down at the same moment, they will slightly alter the earth's orbit, thus countering the effects of global warming. They need 600 million volunteers. They are currently a little shy of this target. If you'd like to make a difference, visit www.worldjumpday.org "