Although most people don't think about it, there is constantly dust accumulating on Earth. All clouds are composed of tiny particles, and inside each is a speck of dust. As rain falls, dust that was suspended in the clouds falls to Earth. Along with dust that is whipped up into the sky from cars, winds, and even us, there is matter from the vacuum of space!
It was commonly thought that exterior dust could not penetrate our atmosphere, but over the course of the last century, scientists have discovered that instead of rapidly accelerating and dematerializing like most objects from space such as meteorites, dust actually slows down in our atmosphere and over the course of a month slowly settles over Earth, increasing its weight!