NASA may be endlessly fascinated with microbial life on far-flung moons in our solar system or testing powerful rocket boosters that will propel humanity off its ancestral home, but there is still a lot we don't know about our own planet — and cosmic dust is one of those mysteries.
What exactly is cosmic dust? Well, it's definitely not the shit you seem to be continually Swiffer-ing off your shelves. That's just dead remnants of you. Eos says cosmic dust "is mostly 4.6-billion-year-old leftovers from the messy accretion process of solar system formation, which the planet picks up as it passes through long-decayed comet tails and remnants of asteroid belt smash ups." Scientists think this dust plays an important role in cloud formation and even fertilising plankton, an essential building block in the Earth's ecosystem — and 54 tonnes of it falls to the surface every day.
That's 24 African elephant's worth of ancient star stuff, or if you don't like the ideas of animals falling to Earth at terminal velocity, about 31 Cadillac Eldorados (from 2002). Scientists first thought the number could be anything between 0.4 and 100 tonnes, but a new paper published in the Journal of Geophysical Research says the number is actually a nice Goldilocks compromise of 54 tonnes.
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