Total Solar Eclipse
By Greenwich HS on November 12, 2012, 5:35pm Last modified: November 14, 2012, 9:37am
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Thanks to the wonderful world of the Intertoobs invented by Al Gore, you have a chance to witness a truly rare total eclipse of the sun Tuesday afternoon. Not live, certainly, since it is only visible in a small sliver of northern Australia. Lucky Aussies. Shucks. According to NASA’s eclipse site , the next visible total solar eclipse for us in North America won’t be till August 21, 2017. Yes, there will be a few “partial” and “annular” eclipses (discussed later), but no total eclipses for a long time. So, hook up your laptops and watch this while you are still young!
So, just what is a solar eclipse and what causes it? Good question. It took us a week to learn this all in Astronomy class – geometric optics, diffraction of light grazing the rim of the moon, illumination inverse square law, and elliptical orbital mechanics – so we will try to condense it all to this one page without all the scary math material. Simple answer is that a solar eclipse is the shadow cast by the moon as it passes directly in between the sun and the Earth. The geometry of the shadow is a little more complicated due to the relative sizes and the hugely huge distances between the objects in question.
So, lets move on to the next slide to begin this astronomical journey...