Properties of Earth Shape Shape Sphere round three

Properties of Earth

Shape

Shape �Sphere – round, three dimensional object �Ways people knew before satellites: • Curved shadow on Moon during an eclipse • Sailors saw top of ships first, then more and more as if it were rising over a hill • As sailors moved north or south, the North Star moved higher or lower in the sky �Not a perfect sphere, wider at equator than the poles.

Shape �Why is the Earth wider at the equator than at the poles? (extremely exaggerated picture!!)

Rotation

Rotation �Rotation – the Earth spinning around its axis �Axis – imaginary line going through Earth • Goes through North and South poles • Titled 23. 5 degrees �Rotation causes day and night; the Sun does NOT move around the Earth.

Magnetic Field

Magnetic Field �Created by movement of core and rotation of Earth �Protects Earth from solar radiation by trapping Sun’s charged particles �Magnetic axis is NOT in the same place as rotational axis • Following a compass to magnetic North Pole would not bring you to the geographic North Pole �Magnetic axis moves throughout time

Revolution

Revolution � Revolution- Earth’s movement (orbit) around the Sun � Orbits are not circular, they are an ellipse • Ellipse – elongated closed curve (basically a stretched circle) � Sun not in center, but off to one side by a little bit � Distance from Sun does not determine seasons (Earth closest to Sun during N. Hemisphere winter, farthest away during summer)

Revolution

Revolution