Measuring Axis Inclination
Date: Winter 2012-2013
How do we know that Earth is tilted at a 23.5 degree angle? How is it measured?
You can go to the equator during the solstices on or about June 21 and December 21 of each year and measure the angle of the sun above the horizon at noon, local time. Fortunately, the people who live down there have already done that and we can take their word for it.
For more information please refer to:
You can go to http://www.google.com and search for ?Solstice? and find many more articles on this subject.
This is a good question. I think the correct answer lies in the stars! The pole star lies in a specific place in the sky, which as Earth's axis revolves over thousands of years. If it pointed straight up Polaris would never be the pole star. I believe that it is the precession off the Earth's wobble that shows that we are angled. To figure the precise tilt is a matter of mathematical calculation Newcomb first did a century ago.
Daviid H. Levy
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Update: December 2011