Phobos is only 20 by 25 km (12 by 16 mi) and has a rapid orbital motion, so someone on Mars would only see the solar eclipse for no longer than about thirty seconds. Phobos also takes only 7 hours 39 minutes to orbit Mars, while a Martian day is 24 hours 37 minutes long, meaning that Phobos can create two eclipses per Martian day. 