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How does a sundial work?
Think about how many ways we have of telling time: watches, digital clocks on kitchen appliances, analog clocks, and more! Before modern clocks were invented, people had to use the sun to keep track of time. Besides just watching the sun in the sky, people could use a sundial to tell time. A pointy part in the middle, called a gnomon, casts a shadow on the plate. As the sun moves across the sky, the shadow changes position and points to markings that show what time it is. It is not as exact as a modern clock that can measure minutes and seconds, but sundials have helped humans keep track of time since the ancient Egyptians in 1500 BCE!
