dipper@utastro.UUCP (Debbie Byrd) (10/29/84)
The Martian sky is pink instead of blue. More -- right after this. October 29 Mars and the Moon If you've never recognized a planet in the night sky, look outside Monday evening for Mars -- the red world orbiting the sun just beyond the orbit of Earth. Monday evening, Mars is near the moon -- it's the fairly bright red object basking in the moon's glare. NASA's Viking spacecraft landed on Mars in 1976 -- they showed, among other things, that the Martian sky is pink instead of blue. Before Viking it was thought that Mars would have a blue sky -- dark blue, like that seen from the top of a high mountain here on Earth. On Earth, the blue sky is caused by the presence of tiny particles in the air -- water droplets, salt crystals, and even molecules of the air itself. These little particles in Earth's atmosphere scatter sunlight in such a way that causes our sky to look blue. A similar process was thought to occur over Mars -- but, since Mars has less air, it was thought that the blue color of the sky would be somewhat darker. When the Viking spacecraft first landed on Mars, the first photos sent back showed a much brighter sky than expected. Special color controls were applied to give a blue tint to the Martian sky in those first photos handed out to the press. A day later it was realized that, from Mars, the sky really does look pink -- due to the presence of fine reddish dust suspended in the Martian air. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin