I've been reading about the Leonid meteor showers and am struggling to understand one piece of information. On Wikipedia (Tempel-Tuttle), it states:
The orbit of 55P/Tempel–Tuttle intersects that of Earth near exactly, hence streams of material ejected from the comet during perihelion passes do not have to spread out over time to encounter Earth. This coincidence means that streams from the comet at perihelion are still dense when they encounter Earth, resulting in the 33 year cycle of Leonid meteor storms. For example, in November 2009, the earth passed through meteors left behind mainly from the 1466 and 1533 orbit.
Why are we going through the meteors left behind by the orbits from 1466 and 1533? What happened to the orbit of 1500 and every subsequent orbit?
My guess is that the perihelion moves slightly from orbit to orbit so the earth moves through a different one each time but I'd love to get an expert explanation!