Comet Hartley 2, officially designated 103P/Hartley, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartleyin 1986 at the Schmidt Telescope Unit in Siding Spring Australia. Its diameter is estimated to be 1.2 to 1.6 km. It will be the subject of a flyby by the Deep Impact spacecraft on November 4, 2010, [...]