False-colour photograph of a Leonid meteor shower. Meteor showers, also known as falling or shooting stars, are caused by microscopic dust grains which enter Earth's atmosphere at speeds between 35 and 95 km per second. The air resistance incandesces the particles, making them visible as streaks of light. Meteor showers occur regularly each year when the Earth crosses the orbit of a comet and its debris enters Earth's atmosphere. The Leonid shower is associated with the P/Tempel Tuttle comet. The image was taken on November 17th 1966 when the Leonid shower reached a record rate of 60,000 per hour for 40 minutes.