Sundial History and Basics

Jacob Tanenbaum · ⏱ 1:58 · 198.2K مشاهدة · 4 years ago

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this is our cottage lane sundial which is located in the garden sundials are an old way to tell the time using only the light from the sun look at this time lapse that took an entire day to film the part of the sundial that sticks up which is called the nomen casts shadow on the face of the sundial when the sun rises in the east the shadow goes to the left of the gnomon as the sun crosses the sky to the west where it sets the shadow moves across the face of the sundial crossing the numbers as it goes and that is what you use to tell the time of course the sundial does not move at all in fact you're not seeing the sun move either what you're watching is the rotation of the earth which is what gives us day and night and makes the sun appear to move across the sky here in the northern hemisphere the shadow moves to the right as it crosses the sundial take look at this analog clock do you see the direction the second hand is going it's the same direction as the sundial in fact we call that rotation to the right clockwise did you know the sundial came first when they were first invented in the 14th century the analog clock was designed to move in the same way as the sundial because people were already familiar with sundials sundials can also help us tell the seasons in winter when the sun is lower in the sky the shadow of the gnomon is much longer and in the summer when the sun is high in the sky the shadow of the gnomon is much shorter sundials are amazing and they are useful but they only work if the sun is out on cloudy days or at night sundials don't work at all