GPHY 102 Lecture Notes - Lecture 3: Spheroid, Great Circle, Circle Of A Sphere
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Gphy102 lecture 3: the earth as a rotating planet. The shape of the earth: earth is an oblate ellipsoid, not a perfect sphere; bulges slightly at the equator, equatorial axis 12,756 km, polar axis 12,714 km, differential (0. 3%) Direction of rotation: earth rotates counter clockwise when viewed above the north pole, when viewed from space it rotates from west to east. Earth"s rotation: earth rotates on its axis once every day or once every 24 hours. Important because: provides the day as a measure of time, axis of rotation provides reference for setting up geographic grid of latitude and longitude. It has an important effect on physical life and processes . System for locating places on earth"s surface: created by the intersection of parallels (lines of latitude) with meridians (lines of longitude) Parallels: circles which are parallel to each other while being perpendicular to the axis of rotation, the equator (0 degrees) is the largest of these, true east-west lines.