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A short history of nearly everythingIn measuring a degree of meridian, the surveyors would create a sort of chain of triangles marching across the landscape. 4 How fast you are spinning depends on where you are. The speed of the EarthБЂ™s spin varies from a little over 1,000 miles an hour at the equator to zero at the poles. 5 The next transit will be on June 8, 2004, with a second in 2012. There were none in the twentieth century. 6 In 1781 Herschel became the first person in the modern era to discover a planet. He wanted to call it George, after the British monarch, but was overruled. Instead it became Uranus. 7 To a physicist, mass and weight are two quite different things. Your mass stays the same wherever you go, but your weight varies depending on how far you are from the center of some other massive object like a planet. Travel to the Moon and you will be much lighter but no less massive. On Earth, for all practical purposes, mass and weight are the same and so the terms can be treated as synonymous, at least outside the classroom. 8 There will be no testing here, but if you are ever required to memorize them you might wish to remember John WilfordБЂ™s helpful advice to think of the eras (Precambrian, Paleozoic, Mesozoic, and Cenozoic) as seasons in a year and the periods (Permian, Triassic, Jurassic, etc.) as the months. 9 Although virtually all books find a space for him, there is a striking variability in the details associated with Ussher ...» |
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