My understanding of the meteor showers that repeat yearly is that the Earth passes through the orbit of a comet that is nowhere near us, and might not even exist anymore, yet it's orbit is filled with a stream of dust in the same heliocentric orbit by way ahead of or behind their cometary source by tens of millions of kilometers or more.
How do these particles spread out along the comet's orbit so far and yet remain tightly correlated transverse to the orbit? Some meteor showers like the "Unicorn shower" linked below can be quite short, lasting only a fraction of a day!
- What makes some meteor showers continue for days, while the "Unicorn shower" can be shorter than one hour?
- Meteor shower predicted to be best viewed BEFORE midnight (for reasons other than the moon)?
- Why are these objects moving at Vastly Different Speeds along the same orbit?
Left: From What (actually) is Jupiter doing to this year's Perseids meteor shower? Right: From Why would the Perseids meteor rate fall off after maximum faster than the increase before maximum? - click each for full size