The Leonids are a prolific meteor shower associated with the comet Tempel-Tuttle. The meteor stream is viewable every year around November 17 and is thought to be comprised of particles ejected by the comet as it passes by the Sun. When the Earth moves through the meteor stream, the meteor shower is visible. The Leonids get their name from usually making their appearance in or near the constellation Leo.
The Leonids are famous because their meteor showers, or storms, can be among the most spectacular. They seem to follow a 33 year cycle, associated with the 33 year orbit of Tempel-Tuttle. Storms in peak years can feature thousands of meteors per hour; notable events were observed in 1698, 1799, 1833, 1866, 1966, and 2001.