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Credit & Copyright: Michael Kunze
Explanation:
Why don't those stars move?
Stars in the sky will typically appear to rise and
set as the Earth turns.
Those far to the north or south will appear to
circle the pole.
If you look closely at the
above time-lapse movie,
however, there are points of light that appear
stationary.
These objects are not stars but
human-launched robotic spacecraft that remain fixed high above the
Earth's equator.
Called geostationary satellites,
they don't fall down because they do orbit the Earth -- they just orbit at exactly
the same speed that the
Earth rotates.
The orbital distance where this is possible is much farther than the
International Space Station but much closer than the
Moon.
The video was taken from one of the
highest
revolving restaurants in the world located on the
Mittelallalin
in the Swiss
Alps.
In the foreground is a mountain known as the
Allalinhorn.
An even closer inspection will show that the
geostationary satellites flash with
glints of reflected sunlight.
The satellites also all appear on a single line --
actually the projection of the Earth's equator onto the sky.
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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