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Date: | Sat, 24 Nov 2012 22:46:49 -0800 |
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ISEN-ASTC-L is a service of the Association of Science-Technology Centers
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He teched...will audition for spring shows in January
He would like you so much but he's so stubborn!
We're happy they're together but miss them and wish we could go to four shows!
How's TK's job hunt?
Deborah Lee Rose
On Nov 24, 2012, at 3:25 PM, Tom Lesser <[log in to unmask]> wrote:
> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related institutions.
> *****************************************************************************
>
>
> On 12th and 13th August 1883, an astronomer at a small observatory in Zacatecas in Mexico made an extraordinary observation. José Bonilla counted some 450 objects, each surrounded by a kind of mist, passing across the face of the Sun.
>
> Hector Manterola at the National Autonomous University of Mexico in Mexico City has placed limits on how close the fragments must have been: between 600 km and 8000 km of Earth. What's more, Manterola and co estimate that these objects must have ranged in size from 50 to 800 metres across and that the parent comet must originally have tipped the scales at a billion tons or more, that's huge, approaching the size of Halley's comet.
>
> Each fragment was at least as big as the one thought to have hit Tunguska. Manterola and co end with this: "So if they had collided with Earth we would have had 3275 Tunguska events in two days, probably an extinction event."
>
> http://www.technologyreview.com/view/425780/billion-ton-comet-may-have-missed-earth-by-a-few-hundred-kilometers-in-1883/
>
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For information about the Association of Science-Technology Centers and the Informal Science Education Network please visit www.astc.org.
Check out the latest case studies and reviews on ExhibitFiles at www.exhibitfiles.org.
The ISEN-ASTC-L email list is powered by LISTSERVR software from L-Soft. To learn more, visit
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