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Credit & Copyright: Trudy E. Bell
Explanation:
Are photographs of star trails really evidence of the
Earth's rotation
about its axis?
Yes they are, and
science journalist Trudy E. Bell discovered that there is a
simple way to demonstrate this, if you have the stomach for it.
First, find a playground equipped with a standard
Merry-Go-Round (MGR)
located under or near a large, leafy tree.
Seat yourself near the middle of the MGR platform.
Ask a local playground expert (KID) to get you
spinning very, very fast.
As the scenery flashes by at a dizzying rate, point your camera
skyward and take a picture with a slow shutter speed setting.
The result will be similar to this excellent image of concentric,
arcing leaf trails centered at a point corresponding to the MGR's
axis of rotation - a convincing imitation of
circumpolar star trails recorded in
hours-long exposures
of planet Earth's night sky.
Then, just stand up and walk away ...
if you still can.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: star trail
Publications with words: star trail
See also: