Wooster Hall stairs at Solar Noon on the Vernal Equinox, 2018

Vernal Equinox in Wooster Hall

The newly updated Wooster Hall has a neat feature at the bottom of the stairwell between the first and second floors. Above that stairwell there is a large skylight with 4 windows, and at the bottom of the stairs there are markings on the floor that show where the shadows between those windows will be at solar noon on the Vernal Equinox (see the image above).

I was able to observe this phenomenon in some detail on Tuesday, 19 March 2018 (which was actually the day before the equinox, but the weather was expected to be cloudy the next day, and indeed it was). When I arrived I found a nice corner to observe from, and although I had not planned to do so ahead of time, I ended up taking a picture just about every minute (and more frequently right around solar noon) for an hour or so. After a little research I was able to write a Python script to put the images together in the following animated GIF  (keep your eyes on the shafts of sunlight moving across the floor):

The speed  is a little rough — I was aiming for one second of animation for one minute of real time but apparently I still need to make some adjustments, and even then it might depend on which browser you are using.

It was a little tricky to do this right, because I was not able to take the photos at regular intervals, and so the duration of each frame in the animation had to be computed from the time of the photo, which was extracted from the EXIF metadata. In case it is of some interest, the details of how I created this animations are in my next post: “Vernal Equinox in Wooster Hall: Irregular Interval Time-Lapse Animation

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