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Why is the shadow moving? Note when the shadow is longer and shorter. Why do you think the shadows changed their length?
Take your sundial outside on a later date to see if you can use it to predict the time based on the Sunʼs shadow. Was your prediction correct? Why or why not?
NOTE: If you are unable to leave your sundial unattended for several hours, you can bring it back and forth with you for each measurement, BUT you must return to the same location where you were standing and face the same direction you were facing each time.
Create a human sundial! Have a friend or family member trace your shadowʼs outline using sidewalk chalk and then return to the same location later in the day to trace a new shadow. Did the shadow change?
If you have a sandbox or youʼre at the beach, you can also make a sundial with a straight stick in the centre and stones around it to mark the hours.
As the Earth rotates, the Sun appears to move across the sky, marking the passage of a day. A sundial helps to measure the time and is made up of a vertical object or “gnomon” that casts the shadow, which in this case is our straw, and a flat surface called a dial. The length of shadow changes with the position of the Sun. That means, the higher the Sun is above the horizon, the shorter the shadow. The Sun is highest in the sky in the northern hemisphere during the summer solstice due to the tilt of the Earthʼs north pole towards the Sun. How does the length of your shadow on the summer solstice compare to its length at different times of year?