Thursday, August 24, 2017

Black Hole Sun


    In the two days that I spent in Eastern Oregon leading up to Monday's total eclipse, I asked a few locals where they intended to view the eclipse.  I was kind of surprised that some of them planned to view from their homes just outside of the path of totality.  Although 99.7% rounds up to 100%  and that is adequate in most situations, it doesn't compare when it comes to eclipses.
99.7%
    When 99.7% of the Sun is covered you're still looking at the Sun.  When 100% of the Sun is covered you're able to see the elusive corona and prominences the filaments of particles attempting to escape the solar surface.
100%
     The eclipsed Sun is comparable in brightness to a Full Moon.
    During the 1 minute 56 seconds of totality I was frantically operating and adjusting 2 cameras, one with a 500mm lens and the other wide angle 28mm lens.  During the fleeting moment of the 'diamond-ring' effect as the last (first) ray of sunlight disappears (appears)  at the beginning (end) of totality, the Sun and Moon combination looks like a ring of corona with one bright point shining like a diamond. At those opportunities I should have been manning the telephoto equipped camera, Instead I only (accidentally) caught it with the wide field camera.
  Crop of photo above shows a diffraction obscured 'Diamond-ring' effect.
     A little longer exposure shows the sparsely illuminated foreground during totality.
   A crop of that photo shows the star Regulus to the lower left of the eclipse. Click on photo below to see it.

   Another neat effect observable during the partial phases before and after totality is that light passing through a small aperture reveals an image of the light source.  Among our group of eclipse watchers was my niece Danielle who's sunhat projected a multitude of mini eclipses on her shoulder. 

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