From: "Alan Friedman" <alan@greatarrow.com>

Date: October 23, 2005 12:11:54 PM MDT

To: <Astro_IIDC@yahoogroups.com>

Subject: Re: [Astro_IIDC] stormy mars comparison image

Reply-To: <alan@greatarrow.com>

Hi Milton -

See the following explanation posted to the mars observers ALPO group by Don 

Parker.

best -

Alan

         The dark region is part of Mare Acidalium. The hood has been 

getting more transparent, which is normal when large dust storms occur. The 

appearance of albedo features through the hood supports Clyde Tombaugh's 

theory that the North Polar Cap isn't present during N. winter but forms 

when the NPH condenses near N. spring. We managed to get an image of this 

in 1993, but this year the evidence is much more compelling. Also the MGS 

has imaged a similar phenomenon for the SPC back in April.   Best, Don <