dipper@utastro.UUCP (Debbie Byrd) (06/03/85)
If you stood on Mars, you might see swirling dust devils that towered miles above your head. More -- after this. June 3 Dust Devils on Mars The planet Mars is now gone from our evening sky. It has fallen so far behind Earth in orbit that it's on the far side of the solar system -- close to the sun along our line of sight -- and lost in the sun's glare. But, while Mars is gone from sight until this fall, space scientists continue to speculate about this nearby desert world. A recent discovery is that huge dust devils may move on the surface of Mars -- swirling towers of red dust. On Earth, dust devils range from inches to the height of several football fields, stacked end to end. On Mars, they appear much taller -- sometimes more than three miles high. The evidence for these huge columns of dust on Mars comes from photographs taken by the two Viking spacecraft, which arrived at Mars in 1976 -- and which took more than 50 thousand images of the planet from orbit. The dust devils on Mars appear to be most common at latitudes near the martian equator, where the sun is most intense. In the photographs, they look like bumps on the desert surface of this world. But their height can be judged by the long shadows they cast against the red desert sand. Some are greater than three miles in height -- most are a mile or two high. What's more, dust devils on Mars are pretty common. At low latitudes, in the relative heat of a martian summer afternoon, there may be one swirling, towering column of red dust for about every 20 by 20-mile patch of ground. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin