Praxis: Telling time by the sun
By Patty Rooks on June 22, 2019.
praxis@praxismh.ca@PraxisMedHat This weekend is the official start to summer!! I know it may not feel like it with nearly one more week of school left, but the sunniest season of the year is here. Summer solstice officially arrived on June 21 at 9:54 a.m. MDT. It was the longest day of the year in the northern hemisphere. Since we are talking about time, I thought it may be interesting to make a sundial so you will be able to tell time all summer long while you enjoy all of your outdoor adventures. Let’s get started! *Remember to ask an adult before doing this experiment. Materials – white paper plate – straw – pencil – red marker – blue marker – scissors – tape – sunny day Procedure 1. Fold the paper plate in half. Make a nice sharp crease in the centre of the plate. Open and fold it in half again. When you open the plate up, there should be an”x” pattern on the plate. This is going to be important. 2. Open the plate up and place it on a flat sturdy surface. Observe it. You should see the “x” pattern. 3. Follow the line from the centre to the end of one of the arms of the x” on the edge of the plate. Place a small circle here with the red marker. 4. Find the second arm of the “x” at the edge of the plate. Using the blue coloured marker place a circle here on the edge of the plate. 5. Repeat with the marker for the other two arms on the “x.” You should now have one circle that is red and three that are blue. 6. These four marks will represent the time of day: 12 p.m., 3 p.m., 6 p.m. and 9 p.m. 7. Set the plate aside for now. 8. Cut the straw in half. 9. Make two slits in the end of the straw. 10. Fold open the straw so you have another “x” shape. 11. Tape this “x” onto the middle of the plate. 12. Go out to a sunny location and place the sundial down. 13. Try to tell the time without looking at a clock! 14. Make a mark with the pencil where the shadow is cast on the paper plate. 15. Check on your watch to see what time it is. This will help orient yourself when trying to tell time again. Try to pick the same place and point the sundial in the same direction. What is going on? Sundials have been used to give an indication of time as long as anyone can remember. Research shows that Greeks, Egyptians, and other great civilizations used the position of the sun in the sky and the shadows it would cast as a measure of time. A sundial is still a practical instrument for telling time in an exact location. The pointer or gnomon in the centre of the sundial casts a shadow on the surface of your plate then the sunlight hits it. As the sun moves through the sky throughout the day, you can even begin to divide the path into equal segments to make your time predications even more accurate. Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, http://www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. NOTE our NEW address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403-527-5365, email: praxis@praxismh.ca. 33-32
