Design a Split Polar Sundial For Your Latitude

Design a Split Polar Sundial For Your Latitude North American Sundial Society Created by: R. L. Kellogg rkellogg@comcast. net Sept 2003 This is an unusual power point presentation. By enabling the Visual Basic macros, you can create your own Split Polar Sundial. The Visual Basic macros have been locked to prevent tampering. If you choose to use this presentation: First, check your power point security setting: Click on “Tools” , “Macro”, “Security…”. Set the security level to “medium”. Exit the Visual Basic code and Power Point program, restart the power point and respond to the dialog box “enable macros”. This will be the normal startup to activate the program features. You are prevented from seeing the Visual Basic code, but if you would like a copy, please email Robert Kellogg at the above email address. 1. Start power point (in “medium” security mode) and “enable macros” 2. On the next viewgraph, the sundial construction slide, enter your school name in the text box. Do not delete this box nor move it “in front” or “in back” of any other object. If you do not care for a name on your sundial, move the text box to the bottom of the slide. 3. At the top of power point, select “slide show” and “view show”. 4. Go to the next slide for dial construction. Click the up and down arrows to select your latitude (+ for north, - for south). 5. Click the “Draw Dial” button. Power Point will draw your Sundial. 6. You may select other latitudes and “Draw Dial” again and again. It clears the display before drawing. 7. You may clear the dial and gnomon by selecting “Clear” 8. End the slide show and print out the Split Polar Sundial slide. 9. Cut out the Sundial. Fold the gnomon tabs up. 10. Fold the Sundial base along dotted lines to form a prism. Glue tab. 11. Place the Sundial in a sunny spot with the high side of the dial pointed North (South for Southern Hemisphere). Read the time. This is “local solar time” and may differ from your clock “standard time”. You can use the Equation of Time graph to correct the sundial to standard time. Variability in the earth’s orbit around the sun, the earth’s axis tilt, and the sundial location away from the longitude of the time zone may cause the Sundial to be up to 45 minutes off.

Tab for Gluing North e 4 PM ter Win stic Sol Win te r So 5 PM Equinox lstic e Equinox N W E AM Gnomon PM Gnomon 2 3 PM Clear 1 38 Draw Dial North American Sundial Society S Su mm e r So 7 AM lstic e tice ols r. S me 8 AM 9 AM 10 11 Sum Lat = 38 Bottom of Dial Glue Tab Here

The Sundial Compared to Mean Time