Astronomy Picture of the Day

Explanation: While meteors do show colours, the colours aren't always seen with the unaided eye. Still, high speed colour film recorded this rainbow-like trail as a meteor streaked through the early morning sky on August 13 above Sedona, Arizona, USA. Part of the annual Perseid meteor shower, this bit of dust from the tail of Comet Swift-Tuttle entered Earth's atmosphere at over 200,000 kilometres per hour. The trail it left glowed briefly as friction with the atmosphere vapourized the dust grain and ionized atoms along its path. The initial green colour is thought to be the glow from oxygen in the atmosphere at altitudes above 100 kilometres or so, while sodium atoms and other constituents of the cometary dust grain itself contribute to the orange hues.