1 1 The Shape of the Earth Unit

1 -1 The Shape of the Earth Unit 1: Planet Earth September 24, 2011 Sanders 2: 02 PM

Shape of the Earth n n Earth is nearly a perfect sphere. Earth is an oblate spheroid, slightly flattened at the poles and bulging a little at the equator. 1 -1 Shape of the Earth 2: 02 PM

Not a Perfect Sphere? n n Earth looks flat on its surface. Due to its daily rotation, Earth bulges about 40 kilometers at the equator. South Dakota 1 -1 Shape of the Earth 2: 02 PM

Oblate Spheroid n n Still, Earth is so close to the shape of a sphere that from any point in space it looks like a perfect sphere. An Oblate Spheroid is a nearly perfect sphere. 1 -1 Shape of the Earth 2: 02 PM

How do we know that we live on a gigantic sphere? n n We have photographs of Earth taken from space. There other pieces of evidence of the shape of the earth. 1 -1 Shape of the Earth 2: 02 PM

Earth’s Shape n n At right are sailboats. As they move toward the round horizon, they appear to sink. At right is a picture of a lunar eclipse. The shadow is cast by the round earth on the moon. 1 -1 Shape of the Earth 2: 02 PM

The North Star 1 -1 Shape of the Earth 2: 02 PM

The North Star n We notice the changing positions of the sun and stars, especially Polaris, as we move over great distances on Earth. 1 -1 Shape of the Earth 2: 02 PM

1 -1 Shape of the Earth 2: 02 PM