13 APR 2012 by ideonexus
Cosmic Dust Raining on the Earth
Morris is fond of citing figures that indicate that about five million metric tonnes of cosmic dust falls on the earth each year. He calculates that over five billion years, we should have accumulated a layer of dust 55 m (182 feet) thick! But if you do the calculation correctly (which Morris does not), it amounts to only a shoebox full of dust over an entire square kilometer. This is so minuscule it can barely be detected even in the best sedimentary records from deep-sea cores, which are un...How much and to what effect?