I remember sitting on my front deck with my telescope watching Mars for a couple hours. The local atmosphere settled and the planetary features and colors were amazing. After a while I kept noticing a speck appearing and disappearing off the edge of Mars. After an hour it had definitely moved substantially. I ran in and checked my observatory software and it was Deimos !! Imagine that, a 7.7 mile diameter object seen visually from 43 million miles away.