WIDELY publicised reports that icy comets the size of houses are continuously
pelting the Earth鈥檚 atmosphere were wrong, say scientists in the US.
Earlier this year, Louis Frank of the University of Iowa claimed to have
found clear evidence that about 30 000 鈥渃osmic snowballs鈥� strike the Earth every day
(鈥淣ot a snowball鈥檚 chance . . .鈥� 12 July, p 24).
Images from an ultraviolet
camera on NASA鈥檚 Polar satellite had revealed dark spots, which Frank believed
were mini comets absorbing the glow of the upper atmosphere.
But in the 15 December issue of Geophysical Research Letters, George
Parks of the University of Washington in Seattle and his colleagues will say
that their analysis of the Polar data suggests that the patches are nothing more
than instrumental artefacts. 鈥淭he results of our study suggest there鈥檚 no
evidence for these snowballs,鈥� says Parks.
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