AS101 Study Guide - Final Guide: Asaph Hall, Orbital Period, Tidal Locking
Document Summary
There appears to be no measurable magnetic field (less than at least 1/800th that of earth"s) although recent measurements by the mars global surveyor (1999) show some weak surface magnetic field signatures. This is a bit of a mystery as likely there was once a magnetic field generated by a moving, liquid, iron core. Deimos (panic) were discovered by american asaph hall in 1877 but are only a few km across and are not even spherical (gravity too low). Phobos orbits in 7 h, 39 min at an average distance of only 9378 km from centre of mars (mars radius is about. 3400 km) its orbital period is shorter than a martian day so it rises in the west and moves across the sky in only. 5. 5 hours (as it is only 28 km across at its biggest part it is seen much smaller than our moon about double the size venus is seen by us).
