is the third in distance from the sun and the fifth largest of the planets
in diameter. The mean distance of the earth from the sun is 92,897,000 mi.
It is the only planet known to support life, although some of the other
planets have atmospheres and contain water. The earth is not a perfect
sphere. The diameter of the earth measured around the North Pole and the
South Pole is about 26 mi., less than the diameter of the earth measured
at the equator. In common with the entire solar system, the earth is moving
through space at the rate of just about 20.1 km/sec (just about 12.5
mi/sec or 45,000 mph) toward the constellation of Hercules.