Lunar Eclipse Spectra for the "Blood Moon."
Taken by Tom King on September 27, 2015 @
Watauga, Texas, USA
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Camera Used: Canon Canon EOS DIGITAL REBEL
Exposure Time: 1/400
Aperture: f/5.6
ISO: 800
Date Taken: 2015:09:28 11:58:38
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Details:
Spectra captured during totality and after the lunar eclipse verifies the reasoning which is offered to explain why the "Blood Moon" appears so red during totality. The stated reasoning is the light illuminating the moon during totality first travels through the Earth's atmosphere, which bends the light's trajectory around the Earth, allowing the light to reach the surface of the moon. This trip through Earth's atmosphere also selectively scatters blue and green light wavelengths, leaving mostly red light to illuminate the moon. The spectrum taken during totality clearly shows the light is dominated by red light, when compared to the spectrum from the fully illuminated moon containing a full range of red, green and blue light wavelengths.
Adding a diffraction grating to the camera's light path allows one to acquire the spectra needed to see this effect.
Details: Canon 300D DSLR, ISO 800, focal length 200mm @f/5.6. Post eclipse exposure - 1/500s. Totality exposure - 10s through Star Analyzer 100 lines/mm diffraction grating.
Photographer's website:
http://www.wataugaskies.net
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