Magnetic fields are 'polar' fields with a North and South polarity.
Gravitational fields have no polarity at all.
At large distances, gravitational fields diminish as the inverse square of distance from their source. Magnetic fields at large distances from their source, decrease as the inverse cube of the distance. You can only detect magnetic fields by using charged particles to measure their deflection. Gravitational fields can be detected by using anything to measure a change in velocity. Copyright 1997 Dr. Sten Odenwald Return to Ask the Astronomer .