Strange Martian Spirals ExplainedStrange Martian Spirals Explained
<table align=right cellpadding=0 cellspacing=0 border=0 width=310> <tr> <td align=center> <p class=small><br />Mariner 9 image of the north polar cap of Mars. The image was taken on 12 October 1972, about one-half Martian month