morgsboi Posted November 26, 2011 Posted November 26, 2011 Crappy little thought........ So Nicolaus Copernicus discovered that Earth rotates in orbit around the Sun in 1543. A year is the time it takes for the Earth to do a full rotate around the Sun. So how did anyone know about years before then. How could it be a measurement of time before it was discovered? People might say that they would know by the position of the sun in the sky, but how can there be any accurate way of knowing that?
iNow Posted November 26, 2011 Posted November 26, 2011 There were many different techniques. Read more about some of them and their history here: http://astro.nmsu.edu/~lhuber/leaphist.html And also here: http://en.wikipedia.org/wiki/Calendar 2
Schrödinger's hat Posted November 26, 2011 Posted November 26, 2011 In the most simplistic sense: It gets cold. It gets warm again. This happens every year. People noticed that their crops, the trees around them, animals and the weather all followed a pattern. It's especially notable if you are near/on the arctic circle because it gets dark for a few days. That is as good a marker as any for the beginning of the next cycle (and the origin of many resurrection myths in winter solstice traditions). If you wanted to be a bit more accurate you could jam a rock or a stick in the ground, and trace its shadow, or mark the point its shadow reaches at noon. follow iNow's links for more details 2
swansont Posted November 27, 2011 Posted November 27, 2011 So Nicolaus Copernicus discovered that Earth rotates in orbit around the Sun in 1543. A year is the time it takes for the Earth to do a full rotate around the Sun. So how did anyone know about years before then. How could it be a measurement of time before it was discovered? People might say that they would know by the position of the sun in the sky, but how can there be any accurate way of knowing that? A year is also the time it takes for the sun to trace out an analemma in the sky; you can measure solstices and equinoxes and you only need an accuracy of a day. Check out Stonehenge.
iNow Posted November 27, 2011 Posted November 27, 2011 A year is also the time it takes for the sun to trace out an analemma in the sky; Like this: http://apod.nasa.gov/apod/ap030320.html 1
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