New research looking at micrometeorites — literally microscopic bits of meteorites, particles of rocks and metals from space that fall to Earth — shows that about 5,200 tons of this cosmic debris settles onto the ground every year. 5.2 million kilos per annum, or about 14 tons per day. At least. That's equivalent to the mass of a garbage truck every day. Oof. Also, this is very wee stuff, smaller than a millimeter in size and some smaller than the width of a human hair. There's no reason to panic *. It slows from interplanetary speeds to basically 0 way up in the atmosphere and then drifts down to the ground. It's no danger, and in fact is quite welcome, since it tells us a lot about what's going on in space.