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"One of the great tragedies of mankind is that morality has been hijacked by religion. So now people assume that religion and morality have a necessary connection."
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Early navigation relied on several natural phenomena; the fixed pole star (or stars, when the pyramids were built) and the north magnetic pole. What can you do if a planet has no stable magnetic field, or if the planet's surface is prone to storms that disrupt the field?
People have made practical use of the Earth's magnetic field since ancient times, but it wasn't until 1600 that William Gilberte, personal physician to Queen Elizabeth, published his astounding De Magnete. In it, he revealed his studies with a "terrella" (a magnetized sphere); he hypothesized that the Earth was itself an immense magnet.
If you're into magnetic fields (and, in fact, we all are - just use a compass!), take a look at the very cool Earth's Magnetic Field Images, an interactive page that allows you to see field strengths at different years in the 20th century. (Courtesy of our friends at NOAA - the National Oceanic and Atmospheric Administration.) (Special thanks to a reader who pointed me to a new URL for the old one!) Comment/Join this discussion (BACK ON!) ( 0 ) | RSS/XML | Blog This | Additional
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