Saturday, August 18, 2012

How high up is the umbra of an annular solar eclipse?

by matsuyuki
Question by : How high up is the umbra of an annular solar eclipse?
From Earth, an annular solar eclipse appears as a solar ring. How high would you have to go up for it to appear as a total eclipse? In other words, how high is the point that that connects the umbra to the antumbra? Let's use the eclipse of May 10, 1994 as an example.


Best answer:
Answer by bikenbeer2000Since the Sun and Moon both appear about 0.5ยบ in diameter in the sky, this is the angle of taper of the Moon's shadow, i.e. about 1/100th of a radian. So for a shadow path width of 100 km on the surface of the Earth, the apex of the cone of the shadow will be about 10,000km above the Earth's surface.
For the 10th May 1994 eclipse, a list of the widths of the annular path is provided here: http://eclipse.gsfc.nasa.gov/SEpath/SEpath1951/SE1994May10Apath.html
Multiply all the widths by 100 to obtain an approximate answer.

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Total Solar Eclipse | Solar Eclipse Information

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