The Earth's rotation

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.

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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.