Unit 1: The Earth in the Universe                                            1   2   3   4

3.1. The movements of the Earth

   The Earth is not static. Our planet makes two different movements:

• Rotation:

      The Earth moves around its own axis from West to East (anti-clockwise).

It takes 24 hours, a day, to complete one rotation.

This movement causes the alternation of day and night.

The Earth's axis is tilted at an angle of about 23.5º

• Revolution

      The Earth moves around the Sun.

      It takes 365 days and a quarter, a year, to complete one revolution.

      This movement and the tilt of the rotational axis cause the seasons.

The imaginary plane that contains the Earth’s orbit is called ecliptic plane. The Earth’s orbit around the Sun is elliptic. For this reason, the distance between the Sun and the Earth varies slightly throughout the year.

-      The aphelion is the point of the Earth’s orbit farthest from the Sun.

-      The perihelion is the point of the Earth’s orbit closest to the Sun.

3.3. Where does the Sun rise? Where does it set? Why do you think

        we see it that way?

3.4. What are the consequences of rotation and revolution of the Earth?