Greenland was discovered without the use of magnetic compasses. The Viking longboats that arrived here in 982 relied on the stars and the sun to maintain their orientation. But it was the compass (a Chinese invention) that enabled later European navigators to bestride the world. It was the compass, too, which revealed that the Earth itself has a magnetic field and thus led to the first serious question about the planet's internal structure: what is down there that generates this field?
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