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1. THE MOVEMENTS OF
THE MOVEMENTS OF
THE EARTH AND ITS
THE EARTH AND ITS
EFFECTS
EFFECTS

2. The movements of the Earth
The movements of the Earth
The Earth moves in
The Earth moves in
two different ways:
two different ways:
• Rotation
Rotation.
.
• Revolution
Revolution.
.

3. Rotation
Rotation
 The Earth rotates
The Earth rotates
(spins) on its own
(spins) on its own
axis.
axis.

4. Rotation
Rotation
 Its axis is an
Its axis is an
imaginary line
imaginary line
between the North
between the North
Pole and the South
Pole and the South
Pole.
Pole.
 The axis is tilted.
The axis is tilted.

5. Rotation
Rotation
 The Earth takes 24
The Earth takes 24
hours to complete a
hours to complete a
full circle = a day.
full circle = a day.

6.  The Earth’s axis is
The Earth’s axis is
not perpendicular
not perpendicular
to the plane of the
to the plane of the
Earth’s orbit.
Earth’s orbit.
 The axis is tilted
The axis is tilted
23.5º with respect
23.5º with respect
to the plane of
to the plane of
movement around
movement around
the Sun.
the Sun.

7. The consequences of rotation
The consequences of rotation
The rotation of the
The rotation of the
Earth every 24 hours
Earth every 24 hours
causes day and night.
causes day and night.
• It is day on the side
It is day on the side
of Earth where the
of Earth where the
sun shines.
sun shines.
• On the other side of
On the other side of
Earth is night.
Earth is night.

8. The consequences of rotation
The consequences of rotation
 Rotation, seen from North Pole, is anticlockwise
Rotation, seen from North Pole, is anticlockwise
(from west to east) .
(from west to east) .

9. So the Sun rises in the east.
So the Sun rises in the east.
 Sunset: when the Sun disappears at the end of
Sunset: when the Sun disappears at the end of
the day.
the day.
 Sunrise: when the sun first appears in the
Sunrise: when the sun first appears in the
morning
morning

10. Revolution
Revolution
 The Earth revolves around the Sun.
The Earth revolves around the Sun.
 The Earth takes 365 ¼ days to complete the
The Earth takes 365 ¼ days to complete the
revolution = a year.
revolution = a year.

11. The consequences of revolution:
The consequences of revolution:
the seasons
the seasons
Three factors cause the seasons:
Three factors cause the seasons:
• The revolution of the Earth around the Sun
The revolution of the Earth around the Sun
• The tilt of the Earth’s axis of rotation respects to
The tilt of the Earth’s axis of rotation respects to
the Plane of the Ecliptic.
the Plane of the Ecliptic.
• The tilt of the Earth’s axis remains constant.
The tilt of the Earth’s axis remains constant.

12. The tilt of the axis causes:
The tilt of the axis causes:
Differences in temperature
Differences in temperature
Differences in the duration of day and night.
Differences in the duration of day and night.

13. Revolution causes:
Revolution causes:
- The four characteristic positions of the
- The four characteristic positions of the
Earth (summer and winter
Earth (summer and winter solstices
solstices and spring
and spring
and autumn
and autumn equinoxes
equinoxes).
.
- The
- The seasons
seasons of the year
of the year

14. Solsticies and equinoxes
Solsticies and equinoxes
 Solstice: one of two days in the year when the
Solstice: one of two days in the year when the
Sun is at its highest or lowest point in the sky at
Sun is at its highest or lowest point in the sky at
noon (12 pm)
noon (12 pm)

15. Solsticies and equinoxes
Solsticies and equinoxes
 Equinox: one of two days in the year when day
Equinox: one of two days in the year when day
and night are the same length of time.
and night are the same length of time.

16. The Seasons
The Seasons
The Sun is not at
The Sun is not at
the exact centre of
the exact centre of
the Earth’s orbit and
the Earth’s orbit and
the Earth’s orbit
the Earth’s orbit
around the Sun is not
around the Sun is not
a perfect circle.
a perfect circle.
So, the distance of
So, the distance of
the Earth from the
the Earth from the
Sun varies as the
Sun varies as the
Earth revolves around
Earth revolves around
the Sun.
the Sun.

17. The seasons in the Northern
The seasons in the Northern
Hemisphere
Hemisphere
During the summer in the northern hemisphere, the Earth is
During the summer in the northern hemisphere, the Earth is
farther away from the Sun. The temperature is higher because
farther away from the Sun. The temperature is higher because
there are more hours of daylight and because the Sun’s rays hit the
there are more hours of daylight and because the Sun’s rays hit the
Earth’s surface at an angle of 90º.
Earth’s surface at an angle of 90º.

18.  During the seasons, temperature changes
During the seasons, temperature changes
depend on angle at which the Sun’s rays hit the
depend on angle at which the Sun’s rays hit the
Earth.
Earth.

20. The seasons are caused by:
The seasons are caused by:
 The movement of the Earth around the
The movement of the Earth around the
Sun.
Sun.
 The tilt of the Earth’s axis of rotation.
The tilt of the Earth’s axis of rotation.
 The fact that the tilt remains constant.
The fact that the tilt remains constant.