  We derive stronger bounds on the magnetic monopole charge of the proton, and
hence on non-associative quantum mechanics from measurements of the magnetic
fields of the Earth, the Moon and Mars. Limits are several orders of magnitude
stronger than the ones inferred from the Hydrogen atomic levels, assuming that
electrons do not retain a magnetic monopole charge. Conversely, we show how to
estimate bounds on the magnetic charge of a proton correctly, when the magnetic
monopole charge of the electron is taken into account.
