> Interesting questions would be "Why vanish in the winter?" Simplest answer...

		keenerd on Oct 3, 2012 \| parent \| context \| favorite \| on: Are Those Spidery Black Things On Mars Dangerous? > Interesting questions would be "Why vanish in the winter?" Simplest answer would be some seasonal event (either a CO2 snow or annual dust storm) covers the markings.