Very special astronomical event today: sciencedepartmenthenge, when (specifically at lunchtime) the Sun shines through a shoebox sized window in the biology store, through the 10cm window in the door, and the whole way down the corridor through small windows in the fire doors.
Plus it's extra special: the last one before we move to a new school and the current one is demolished.

This happens over maybe a 30 day period, mid November to mid December, but each instance only lasts for a minute or two, and needs both full sunshine (have you met Scotland?) and for me to be there to notice. I put a few non-essential jobs off to track this for 10 minutes as the beam tracked towards its target.

This is last year, caught on the 12th of November, but not as full on. https://mastodon.social/@_thegeoff/113472289742351255

I pointed it out to the physics teacher, who at least remembered it was a thing! And a student who was unlucky enough to be passing, and admitted it was "pretty cool".

@_thegeoff It's remarkable how quickly shadow edges move. Makes it easier to remember we live on a giant ball of rock hurtling around a nuclear inferno.

@varx Yup, the corridor has to be about 50 metres long, with a window about 20cm wide halfway along, so that's not much angular space to play with, enough to make you dizzy if you think about it too hard. 😎

@_thegeoff I guess the limit on the fastest moving shadow would be based on the crispness of the shadow edge, right?

Like, you could cast a *really* long shadow off of a tall post around sunset, but it gets fuzzier the farther it goes out, and at a certain point you stop being able to see the edge...

@varx That's going to be partly based on the "crispness" of the aperture edges it passes through though, and windowframes made of razorblades are contra-indicated for high school settings 😉

@_thegeoff Ooh, interesting... this is one of those optics things that I've never actually understood. Gotta play around with this a bit. :-)