Researchers at the Jet PropulsionLaboratory in Pasadena, California,US, have discovered a star in theconstellation Ophiuchus, which ison a collision course with the OortCloud, a region on the outskirts ofthe solar system containing billionsof comets. If it hits the cloud, thestar will send thousands of cometstowards the sun, jeopardising theEarth. The star, Gliese 710, is about100,000 times the size of the Earthand is moving towards us at a speedof 14 kin per second. But it is 63 lightyears away and it will take anothermillion years for the collision totake place (New Scientist, Vol 154,No 2083).