Space/Science — HabitableZone

Space/Science » in reply to re: Um. An optical illusion of what?

Right on with the streaks, but be aware of summer images, too
nick hoffman — (archived)

As soon as the frost is all gone, we don't see these dust stains any more. All we see is near-uniform tan-grey dust and rock. There's a contrast issue with MOC in that it only has limited image depth (digitally speaking). As I recall, these are only 7-bit images, and the human eye can resolve more than 8-bits, especially in colour. MOC has both automatic and manual contrast-stretching and exposure control routines that tend to emphasise contrast at the expense of absolute intensity. This allows us to capture useable images in Summer sunshine as well as in "pre-dawn" conditions over the polar icecap.

What looks like black and white is in fact grey and white. This can be derived with laborious effort from the image data. In summer we see shades of grey with no white frost. The dark streaks of springtime are identical in colour to the underlying grey-tan dust and therefore appear invisible once the contrast-supplying frost has sublimed.

Note that we're talking about locations off the permanent icecap here. ON the icecap we don't see geysers, dark plumes, spiders, or anything like that. Instead we get a different set of wierd features such as swiss-cheese terrain as layered CO2 ice sublimes in strange circular and arcuate patterns like Liesegang rings (as seen in growing lichen patches, fairy rings of fungus growing on lawns, and the amazing "traffic light" chemical colour change reaction)

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