Monday, July 27, 2015

Ceres provides a hazy clue


Back a few posts ago, I predicted that the mysterious bright spots on Ceres (the dwarf planet, formerly known as a big asteroid) would turn out to be ice in some form.   Here's what I wrote:

"I'm going to hazard a speculation here. The spots are ice. (Wow, major speculation effort.) What I'm expecting is that there is going to be some unique asteroidal geological process in that location that keeps the ice "fresh" and reflective, i.e., not covered by regolith -- another word for dust.  
What that process might be -- I have no clue. But I don't think that they are vapor, like a gas jet, because they are too immobile and there has been not a mention of any kind of Cerean atmosphere with a little tenuous water vapor."
 Well, surprise, surprise, surprise -- I was sort of right by being wrong.  Two articles (there are more, but here's two):

Mystery haze appears over Ceres' bright spots

Strange Bright Spots on Ceres Create Mini-Atmosphere on Dwarf Planet

" "If you look at a glancing angle, you can see what seems to be haze, and it comes back in a regular pattern," Dawn principal investigator Christopher Russell, of UCLA, said during a presentation Tuesday (July 21) at the second annual NASA Exploration Science Forum, which took place at the agency's Ames Research Center in Moffett Field, California."
OK, so they probably aren't vapor, but because they might possibly be ice, they appear to be releasing vapor -- water vapor, of course.

So, speculating -- if these ice spots release enough water vapor, that keeps the dust off, which is what keeps them bright and reflective.

I like that.  But why (even though there are other small bright spots on the dwarf planet), are these big bright spots just in one crater?

Hmmm...




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