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Speaker 1: Welcome to brain Stuff past him Marshall Brain. On the news,

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Speaker 1: you'll often hear people, especially boat and airplane people, talking

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Speaker 1: about nautical miles. Have you ever wondered why there's more

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Speaker 1: than one kind of mile? A normal mile is five thousand,

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Speaker 1: two d eight feet, and that's a totally random unit

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Speaker 1: of measurement. A nautical mile is instead based on the

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Speaker 1: size of the Earth. If you take the circle of

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Speaker 1: the Earth at the equator, you can divide that circle

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Speaker 1: into three hundred sixty degrees. You could then divide each

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Speaker 1: degree into sixty minutes. A nautical mile is a minute

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Speaker 1: of the Earth's arc. If you travel one degree around

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Speaker 1: the Earth, you've traveled sixty nautical miles. Three hundred sixty

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Speaker 1: times sixty is one thousand, six hundred, so it's twenty

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Speaker 1: one thousand, six hundred nautical miles around the planet. Coincidentally,

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Speaker 1: a kilometer is also based on the planet Earth. Take

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Speaker 1: the distance from the north pole to the equator, divide

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Speaker 1: that by ten thousand, and you have a kilometer. For

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Speaker 1: more on this and thousands of other topics, go to

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Speaker 1: how stuff works dot com. M