Google has joined the UN, Harvard University and a pressure group founded by George Clooney to use satellites to scour Sudan for evidence of state-organised violence before next month’s referendum that could see the country split in two. Clooney said that he had launched the Satellite Sentinel Project to “stop a war before it starts” by warning the government in Khartoum that it would not be able to hide war crimes from the rest of the world, as it did for so long in Darfur, if there is violence in southern Sudan, which is likely to vote on 9 January to secede.