[meteorite-list] Cosmic Dust on Earth

[Ron Baalke]

http://www.nature.com/nature/links/041223/041223-1.html

Nature Highlights
Cosmic dust on Earth

Meteoritic smoke particles form when extraterrestrial particles burn up
on entering the Earth's atmosphere. Metal atoms associated with this
process are used as a proxy for interplanetary particles, but their fate
has long been a mystery. Analysis of a Greenland ice core reveals
iridium and platinum fluxes consistent with constant fallout of
extraterrestrial matter over the past 10,000 years, and potentially
during the last ice age. Model studies suggest that most of the cosmic
material is carried to the polar regions by the prevailing winds above
60 km before funnelling down to the surface, and that there is a yearly
global input of 14±5 kilotonnes of this meteoroid material to the Earth.
The cover photo, taken by Torbjörn Lövgren in Kiruna, Sweden, records an
extremely rare event, a meteor fireball seen against a green aurora.

letters to nature

Meteoric smoke fallout over the Holocene epoch revealed by iridium and
platinum in Greenland ice
PAOLO GABRIELLI, CARLO BARBANTE, JOHN M. C. PLANE, ANITA VARGA, SUNGMIN
HONG, GIULIO COZZI, VANIA GASPARI, FRÉDÉRIC A. M. PLANCHON, WARREN
CAIRNS, CHRISTOPHE FERRARI, PAUL CRUTZEN, PAOLO CESCON & CLAUDE F. BOUTRON
Nature 432, 1011?1014 (2004); doi:10.1038/nature03137
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