s fall into the Earth
all the time... ton
s of them every year. But when the Earth passes through the debris left behind
by a comet
, then you get lots of meteors at once.... a shower
The most activity is usually just before local dawn that's when you are rotating in the same direction that the Earth is travelling around the Sun.
A couple of examples: the Perseids (around August 12) and the Leonids (around November 17).