The sun is a much more powerful magnet than the earth. In fact its magnetic field is about a hundred times as strong, and its magnetic moment is a hundred million times that of the earth. In other words every rotating body is a magnet. The sun was first suspected to be a magnet because the streamers in the corona, which is seen round it during an eclipse, have a pattern like that which iron filings take up in the neighbourhood of a magnetized steel ball. The magnetic moment of Babcock's star is about ten thousand million times that of the earth. The theory may facilitate work on atomic nuclei, by helping us to understand how a neutron, though it has no electric charge, behaves as a magnet. More likely it will help in the framing of a cosmology which will link together gravitation and electromagnetism more satisfactorily than Einstein's theory of general relativity.