Phobos never failed to intrigue me. From Wikipedia: Phobos's unusually close orbit around its parent planet produces some unusual effects. As seen from Phobos, Mars would appear 6,400 times larger and 2,500 times brighter than the full Moon appears from Earth, taking up a quarter of the width of a celestial hemisphere. Some nice pictures of Mars, including Phobos, can be found here: http://www.boston.com/bigpicture/2008/06/martian_skies.html