Wednesday, March 01, 2017

July 17, 2016: Pale white disk in a pewter sky

That's no moon...
Saturday, July 16, 2016, rain fell hard in Northeastern Pennsylvania. It left the ground saturated, and the air as well. The next morning a fog formed, hiding the rising sun.

I was scheduled to work that day. I went through my normal morning routine: make coffee, feed the cats, eat breakfast, get lunch together. As I washed my breakfast dishes I glanced out the window over the kitchen sink. A strange pale disk hung in the pewter-gray sky, Moon-sized but not the Moon.

I knew not to stare. Even with miles of fog and clouds attenuating the onslaught, there was still plenty of ultraviolet and infrared radiation heading into my eyes. But I wondered: could I safely take a photo of the fog-dimmed Sun?

I decided to chance it. I would use the high shutter speed setting that I routinely use for imaging the Full Moon. I would aim the camera freehand, to reduce the risk that I would burn out the imager.

I started out with the context-setting image above. In addition to shooting through fog and clouds I also had a layer of window glass between me and the Sun. Window glass inevitably has dirt on it, especially after a rainstorm. I worried that dirt might mess up any image I took. Reviewing my first shot, I saw that my fears might have been justified. There were spots on the Sun.

Aw, geez. Spots on my image of the Sun.
I changed position, took another image of the Sun through another part of the window. Same spots. The spots were on the Sun, not on the window.

Same image as above, brightness and contrast adjusted.
I tweaked the best image by adjusting the brightness and contrast to enhance what I now knew to be sunspots. Surprisingly, the image also seemed to show granules, the convection cells that break up the surface of the sun, though that could just be an effect of the clouds and fog and image enhancement. The image also showed obvious limb darkening, which is a real thing and not an image artifact.

SOHO image showing sunspots for July 17, 2016
I pulled up the SOHO daily sunspot image for that day and compared it to my image. Rotated about 50 degrees,  it was a perfect match. So thanks to fog, clouds, and my Nikon Coolpix p520, I had just gotten an image of the Sun, with sunspots!

NOTE: DON'T TRY THIS AT HOME. There are special filters that will allow you to view and photograph the sun safely, without risking damage to your eyes or camera. I was not using any of these. I got lucky because of the extreme atmospheric dimming. You might not.

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