Astronomy Picture of the Day

Discover the cosmos! Each day we feature a different image or photograph of our fascinating universe, along with a brief explanation written by a professional astronomer.

November 14, 1995

Aurora and Orion
Credit: NASA, STS-59 Crew.

Explanation: 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.

Tomorrow's picture: A Quintet of Galaxies

Authors & editors: Robert Nemiroff (GMU) & Jerry Bonnell (USRA).
NASA Technical Rep.: Sherri Calvo. Specific rights apply.
A service of: LHEA at NASA/ GSFC