Aurora and Orion
Credit:
Looking toward the south from low Earth orbit, the crew of the
Space Shuttle Endeavor made this stunning time exposure of the
Aurora Australis (southern lights) in April of 1994.
The aurora
are caused by high energy electrons from the
Solar Wind
which are funneled into the atmosphere
by the
Earth's magnetic field.
The reddish colors occur at the highest altitudes (about 200 miles)
where the air is least dense. At lower altitudes and greater densities
green tends to dominate. At the lowest altitudes a pinkish glow is
sometimes produced.
The familiar
constellation of Orion the Hunter is clearly
visible above the dark horizon in the background.
Because of the shuttle's orbital motion, the bright stars
in
Orion appear slightly elongated.