How to Tell Time With Your Shadow

Your shadow gets shorter in the middle of the day.
••• Seiya Kawamoto/Lifesize/Getty Images

Sunlight shifts over the course of a day, hitting the Earth directly around noon, from the east in the morning and from the west later in the afternoon and early evening. For centuries, people have used sundials to tell time based on sunlight’s changing directions and its effects on shadows. At different times of the day, your shadow gets longer and shorter, or may disappear. You can tell the time based on your shadow’s current length.

    Determine the latitude and longitude of your current location. You can use a GPS or enter your address at the World Atlas site to find it.

    Measure and record your height in feet and inches.

    Enter your latitude, longitude and height at the Personal Sundial site to return a chart. The chart will show the exact lengths your shadow will be at certain times throughout the day, broken down by months.

    Stand outside in a clear spot so your shadow projects on the ground rather than a wall. Have a helper measure the length of your shadow. Your shadow will be longer in the beginning and end of the day, and shorter toward the middle.

    Look up your shadow’s length on the Personal Sundial chart to determine the time.

    Things You'll Need

    • GPS
    • Measuring tape

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