Measuring the Diameter of the Earth's Shadow

During a Lunar Eclipse: 15th Image

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You can find the center of any circle using three points on the circle. Two cords on the circle have been drawn using the three points A, B, and C on the circle. The intersection of the two perpendicular bisectors of the cords indicate the center of the circle. The circle is continually drawn as the points are moved.

 

1. Move points A, B, and C to the edge of the moon to find out the relative size of the moon (in pixels).

2. Move points A, B, and C to the edge of the earth's shadow to find out the relative size of the shadow.

3. What is the relative size of the shadow of the earth compared to the size of the moon?

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