re: Whew...
Put it this way - at 1k/pixel for Marci - HiRISE can put 3000 pixels on the page for every one of Marci :) So at 5 pixels wide, HiRISE, if they had taken imagery at the same time - would have had a picture of earth 15,000 pixels across. And dont laugh -it can really do that - it's field of view is 20,000 pixels across - the central 4000 being in Red, Near IR and Blue-Green
MRO will be a LOT further away come the time when HiRISE is pointed at earth to test it out - but it'll still be an amazing image to look forward to.
Doug