This video references Zero Shadow Days.Further information on sundials can be found here: Sundials - Sky at Night Magazine.This video references Egyptian Sundials.Shadows have been used for centuries to tell the time.Transparent - objects allow light through.Translucent - objects partially block light.Multiple light sources cast multiple shadows. The shape and size of shadow depends on distance and angle to the light source.Anything that blocks that light, casts a shadow. Let’s explore shadows in more detail – and learn how to turn your shadow into a clock! What are shadows? How are they made? What factors affect their size and shape? Shine a torch on it and see if they can tell what it is, from the shadow that it casts. Make a shape from a piece of scrap paper – but don’t show it to your friends. Now you know about shadows – why not play a game? Zero shadow days occur when the sun is directly overhead. ![]() Nowadays, when flood lights shine on a football pitch from all directions at night, players can cast four different shadows at once!īut twice a year, people who live on the equator cast no shadow at all. We may have technology to tell the time now, but shadows are always there if we need them. Well, before clocks were invented, the ancient Egyptians used sundials to tell the time with shadows – three and a half thousand years ago! If the sky is overcast, our shadows can seem to disappear completely! When the sky becomes cloudy, the sunlight that gets through is spread over a wider area.ĭiffuse light casts shadows that are softer and blurred around the edge. The size of shadows changes throughout the day.Įarly in the morning and early evening, when your part of the Earth is further away from the sun, shadows are at their longest.īut towards noon, as you get closer to the sun, shadows are at their smallest. That's because the Earth travels around the sun, rotating on its axis. You’ll see how, as the light got closer, the shadow got larger.ĭid you know that half the world is always in shadow? Now, move the torch closer, and draw around the shadow again. Using your torch like the sun, shine it on an object and draw around the shadow it casts on a piece of paper. You can use shadows to conduct experiments. The smaller the distance, the larger the shadow. The larger the distance, the smaller the shadow. The size of a shadow depends on the distance between the light and the object. Then the shape of a shadow can change too. ![]() Or the light shines from a different position. Unless, of course, the object is at an angle. Light travels in a straight line – that’s why shadows are the same shape as the object that makes them. Or translucent objects like this clear silicone lid.īut a shadow forms when an opaque, or non-transparent, object blocks light from passing through and reaching a surface on the other side. Light can travel through transparent objects, like glass, They’re dark patches of shade where light does not reach.
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