Astronomy Picture of the Day



Kalamalka Lake Eclipse

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zorg.ch
#103121 by @ 02.09.2007 00:00 - nach oben -
Kalamalka Lake Eclipse


Explanation:

Recorded on August 28th, this serene total
lunar eclipse sequence looks southwest down Kalamalka Lake toward
the lights of
Coldstream,
British Columbia.

An exposure every 4 minutes captured the Moon's position and
eclipse phase, until the Moon
set behind the town lights and a hill on the horizon.

In fact, the sequence effectively measures the duration of the
total phase
of the eclipse.

Around 270 BC, the Greek astronomer
Aristarchus
also measured the duration of lunar eclipses - though probably without
the benefit of digital clocks and cameras.

Still,
using geometry, he
devised
a simple and impressively accurate way to calculate
the Moon's distance, in terms of the radius of planet Earth,
from the eclipse duration.




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