3. THE EARTH’S ROTATION -
The Earth has two motions, rotation and revolution. ROTATION - The Earth rotates once on its axis every 24 hours. This movement has two consequences:1. Day and night 2. The Sun’s apparent movement. - DAY AND NIGHT: - Due to the Earth’s rotation, when the Sun is illuminating a part of the Earth (Day ), the other part is in darkness (Night). - None of the Earth’s parts are too hot or too cold. SUN’S APPARENT MOVEMENT: 1 - If we look up the Sun during the day , it seems to be rising in East and setting in West. It isn´t real. It causes because the Earth rotates in the opposite direction (from West to East). 2- It’s usseful for orientation and we can establish the cardinal points (North, South, East and West).
3. THE EARTH’S ROTATION TIME ZONES
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Because of the Earth’s rotation, parts of the plante are in sunlight and others in darkness. Solar time isn’t the same on all parts of the Earth.
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We divide the Earth into 24 time zones, that correspond to 24 hours of a day. As the Earth is a sphere of 360º, each time zone is 15º. In each time zone there is one hour. - some countries adjust the boundaries of time zones to the political frontiers.
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- Our point of reference in The Greenwich Meridian, at 0º.
As we go east through each time zone we set the watch forward by one hour. As we go west through west time zone, we set the watch back by one hour. -
INTERNATIONAL DATE LINE 1. It’s opposite the Greenwich Meriridian 2. It’s at 180º longitude (it’s a meridian) 3. We put the date forward o r back by a day when we cross this line.