Guest post by Alec Rawls
With a weak sun well up in the clear blue sky yesterday morning I was thinking I should go punch a hole in some cardboard and project an upside down image of just how far sun was being eclipsed by the moon. Then I looked down and saw this:
Wow, about 95% eclipsed. On the Olympic Peninsula, 200 miles north of totality, this must have been about the peak. Small wind-driven movements in the leaves above are presumably why some arcs show up as thicker than others (notice the bit of blurriness in the non-instantaneous arc images). Bigger leaf gaps, being less pinholey, will also enlarge and distort the “pinhole” images. Thus the thinnest arcs would seem to provide the truest representations, coming from smaller leaf-gaps and showing less leaf movement.
Did anyone else see this leaf-gap pinhole-image effect? I wonder how many prehistoric humans saw it and what they pondered about the coincidence between these unusual shadows on the ground and the weak sun above. There are many places where trees overhang flat bare rock surfaces, especially along rivers where humans have often resided.
A short while later the leaf-gap images showed eclipse-coverage at more like 80%:
West is to the left in this picture, verifying the inverted nature of the pinhole images. Just as the earth rotates towards the east so does the moon’s orbit proceed between the earth and the sun from west to east. It turns out that the eclipse shadow passes across the surface of the earth faster than the earth rotates so the shadow proceeds along the ground in the direction of rotation, from west to east. If the ground moved faster than the shadow then the path of totality would proceed east to west along the ground but the moon would still exit totality towards the east.
I did not have eclipse glasses but for those who did, this is what you all observed, correct? That the moon departed totality towards the east? In the leaf-gap pinhole image above the shadow cast by the moon is seen exiting stage west, confirming that the eclipse-image is flipped.
And that is how I saved my retinas, August 21, 2017. Thank you momma nature. I just regret I wasn’t more systematic in recording the progress of the leaf-gap inverted-eclipse-image phenomenon. Next time somebody should get a full sequence of pictures.