dipper@utastro.UUCP (Debbie Byrd) (08/20/84)
This is the anniversary of an early glimpse of the icy poles of the planet Mars. More on the poles of Mars -- right after this. August 13 The Poles of Mars The planet Mars is like Earth in many ways -- for one thing, it has ice at its poles, just as Earth does. The icy polar caps of Mars are visible through small telescopes as white patches on the red disk of the planet. They were seen for one of the first times on today's date in the year ____ by Christian Huygens -- a 17th century astronomer who's also famous for being the first person to recognize the rings of Saturn as rings. The poles of Mars are ice -- but not all water ice. During the Martian winter, carbon dioxide freezes out of the air and forms a frost layer on the ground at the winter pole. When summer returns, and that pole warms up, the carbon dioxide goes back into the air -- only to freeze out again at the other pole during winter on that part of the globe of Mars. So much carbon dioxide shuttles back and forth between the Martian poles that the total air pressure on Mars varies seasonally by more than 25 per cent! The poles of Mars would be fascinating places to explore. Martian winds appear to carry dust to the polar regions -- making vast fields of dunes. The layers of ground beneath these Martian dune fields may contain a wealth of information about the geology of the red planet. When scientists someday explore them, the polar regions of Mars may provide important clues to the planet's history. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin