Extra Credit 2

Make a working sundial!

Make a working sundial, that you can actually use to tell time. For full credit, you must:

• show the hour markings on your sundial
• set up and align your sundial to show the class that it actually works!
• answer the following questions:
  1. In a sundial, what is the gnomon?
  2. How many degrees does the sun move across the sky, in 1 hour?
  3. What is the latitude of Tucson?
  4. What is the “Equation of Time”?
  5. On the day that you’re going to show us your sundial, what is the time-correction to your sundial using the “Equation of Time”? (HINT: See the curve in the Wikipedia article below, and find an on-line “Day of Year Calendar for 2015”)

Suggestions and hints:

You may make your sundial out of any materials that are cheap/free and easy to use (paper, plastic, cardboard, string, straws, chewing gum, etc.)–it doesn’t have to be made of marble and brass!

Some very useful web references on sundials include:

https://en.wikipedia.org/wiki/Sundial
http://www.sundials.co.uk/projects.htm
http://sundials.org/

…..but there are MANY OTHERS! …..

Perhaps the easiest sundial to make is one that has the hour markings equally-spaced, known as an “Equatorial Sundial.” (The sundial in front of Flandrau Planetarium is known as a “Horizontal Sundial” and is even easier to make–plant a stick in the ground and locate its shadow. However, if you noticed on the sundial in front of Flandrau, the hour-markings are NOT evenly-spaced, making them much harder to mark on the sundial you build. Evenly-spaced markings can be easily made using a protractor!)