Magnetic Earth and Magnetic Sun

Part of the Astronomers’ Universe Series book series (ASTRONOM)


Magnetic compasses were in use for many centuries before it was finally guessed how they worked. The breakthrough came with William Gilbert, physician to Queen Elizabeth I, who showed that compasses point in a particular direction on the Earth’s surface because the Earth itself is a great magnet. By the beginning of the seventeenth century people knew that pieces of magnetized iron could affect which way nearby compass needles pointed. The needles always point toward one end of the magnet and away from the other end. This is very similar to what happens on the Earth’s surface, where compasses always orientate themselves in a more or less north—south direction. (By analogy with the Earth, magnets are therefore said to have north and south poles.) Gilbert suggested that the Earth’s interior was essentially a large magnet, lined up roughly north—south, and this was what forced compass needles at the surface to line up in the same direction.


Solar Wind Solar Cycle Inner Core Magnetic Activity South Pole 
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