Important pedantic point: There are no gravitational dipoles, as there is no repulsive gravitational interaction. A dumbbell-shaped mass is the sum of a gravit

Important pedantic point: There are no gravitational dipoles, as there is no repulsive gravitational interaction. A dumbbell-shaped mass is the sum of a gravitational monopole and a gravitational quadrupole. That gravitational radiation originates only from quadrupolar sources (which are far less-efficient radiators than an equal-sized dipole) is one reason that gravitational waves are hard to detect.