Cosmic dust in the gutters

Some real peculiarities here

By Jason Daley
smithsonian.com
December 8, 2016

Antarctica is the go-to spot to collect cosmic dust—the tiny grains of space rock that date back to our planet's infancy. These specks from space are challenging to find and previously thought impossible to separate from the chaos of urban debris.

But a new study, recently published in the journal Geology, suggests that cosmic dust may be found closer to home. Matthew Genge from Imperial College London and amateur Norwegian scientist Jon Larsen combed through 660 pounds of gunk collected from gutters in Oslo, Paris and Berlin, finding 500 particles of cosmic dust, according to a press release.

“We’ve known since the 1940s that cosmic dust falls continuously through our atmosphere, but until now we’ve thought that it could not be detected among the millions of terrestrial dust particles, except in the most dust-free environments such as the Antarctic or deep oceans,” Genge tells New Scientist. “The obvious advantage to this new approach is that it is much easier to source cosmic dust particles if they are in our backyards.”

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These urban micrometeorites also suggest that the dust making it to Earth has changed over time, according to the press release. Dust captured in Antarctic ice is much more ancient, accumulating over the last million years. And unlike these minute particles, the urban cosmic dust contains feather-like crystals. The urban particles are, however, similar to dust that has fallen since Medieval times.

The difference in size is probably caused by slight changes in the orbits of Earth and Mars, Genge explains in the press release. This change affects the gravitational pull on the particles, causing them to come in faster and heat up more, which alters their size and shape. Those changes, he says, are important to understand if cosmic dust is used to reconstruct the geologic history of the solar system….