The good thing about this recapitulation of controversy for its own sake is that we can come to appreciate how light and bright the lighter regions of Mars really are. Well. At least in a relative sense. Actually, I understand that even the bright white poles are "dusty" and are relatively red compared to a pristine white.

I'm not sure of Christensen's point. "White Rock" is -- relatively -- very bright indeed, close enough to "white" for most purposes, though obviously not as white as the whitest possible deposit on Mars, not even as white as the dusty poles. To say it is "quite red" is relatively meaningless. "Quite red" compared to what?

For example, are the "white" outcrops in this Pathfinder image really white, or are they really "quite red?"

Are these outcrops relatively the same color and possibly the same composition as the many "White Rock" deposits found on Mars? And what would that composition be? Can it be determined from afar?

And when you look through your telescope at Mars (and you are actually looking during this never-before-and-never-again-in-our-lifetimes opposition, aren't you?) what do you see? Does the surface of Mars appear to be a pale mottled ruddy tan? Or do you see a bright pink or butterscotch surface?

Cheers, BRFelix