Maggie McKee writes: "Kamchatkans and Venezuelans beware. A 20-million-tonne asteroid could be heading your way. Californians have even more reason to worry — the asteroid is more likely to hit the Pacific Ocean, triggering a tsunami that could devastate the west coast of North America. These are among the scenarios projected for asteroid Apophis, which researchers now say has a 1 in 45,000 chance of hitting Earth on 13 April 2036. Calculations show it would strike somewhere along a narrow track that stretches eastward from Siberia to the west coast of Africa. The threat, while small, is real enough to merit a United Nations protocol for dealing with the problem, experts say."