When I posted that bit about micrometeoritic dust, I could neither find the original quote nor verify it from any online source (in a quick look), but I just found it on an archive CD. (See, I AM organized!)

"Every hour, the Earth puts on a ton of weight in the form of micrometeoritic dust: ...bits of defunct comets, grime ground off colliding asteroids, and of powder left behind when the planets formed."

So that's TWENTY-FOUR TONS a day! -- No wonder none of us can keep up!

I still haven't found the source of the quotation, but my educated guess says it is probably an article, circa late '90s, in Smithsonian magazine.

Linn