Monday, April 28, 2008

Analemmatic Sundial v1.0

For science today, the kids and I drew a giant analemmatic sundial in the road with chalk. We used the calculations I made and laid it out according to these plans. I even made sure to adjust it for daylight savings time.

Does it work?

Well, it would work, if I hadn't very stupidly tried to draw a five-foot-long north-south line using a five-inch long compass. I really should have known better. And I forgot to correct for true north vs. magnetic north. As a result of my errors, my sundial is about half an hour off. (And it would have worked, too, if it weren't for those meddling kids!)

So here are my tips for v1.1:
  • Use a board much lighter than a 2x6 for your giant ruler.
  • Get a large try-square.
  • Make sure your "helpers" do not have access to distracting Legos during the time when you are drawing the sundial.
Sundial v2.0 will be permanently drawn on a tarp, which can be laid out and staked down. As long as it's properly aligned to north, it will work anywhere on your latitude, provided the sun is shining.