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.
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It's those few days of the year, ScienceDepartmentHenge, when the sun shines through a small 60cm window at the top of the biology store, through a narrow window in the biology store door, through a narrow window in the mid-corridoโฆ
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".
@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. ๐
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 ๐
@varx Hold your finger and thumb up to a bright light. Close one eye. Watch the thumb and fingertip "reach out and join each other" just before the actually touch ๐
Hah! I still need to mess around with that some more too.
OK, I used the flashlight on my phone to project light on the wall. The closer my finger is to the light, the fuzzier the shadow. But holding a knife broadside to the light at the same distance still casts a shadow that's just as blurry.
Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •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. mastodon.social/@_thegeoff/113โฆ
Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ (@_thegeoff@mastodon.social)
Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ (Mastodon)Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •varx/social
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ reshared this.
Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ
in reply to varx/social • • •varx/social
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •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...
Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ
in reply to varx/social • • •varx/social
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ
in reply to varx/social • • •varx/social
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •Hah! I still need to mess around with that some more too.
OK, I used the flashlight on my phone to project light on the wall. The closer my finger is to the light, the fuzzier the shadow. But holding a knife broadside to the light at the same distance still casts a shadow that's just as blurry.
Ross of Ottawa
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •Glob
in reply to Geoff ๐ด๓ ง๓ ข๓ ณ๓ ฃ๓ ด๓ ฟ • • •