Two movements of the Earth
The Earth is always moving in two ways. Rotation is the spinning of the Earth on its own axis, taking about 24 hours for one full turn. Revolution is the movement of the Earth around the Sun in its orbit, taking about 365¼ days (one year).
Effects of rotation
- Day and night — the side of the Earth facing the Sun has day; the side facing away has night.
- Difference in time — as the Earth spins, different longitudes face the Sun at different moments.
- Apparent movement of the Sun — the Sun seems to rise in the east and set in the west.
Key idea
Rotation (spinning on its axis, ~24 hours) gives us DAY and NIGHT. Revolution (orbiting the Sun, ~365¼ days) together with the tilted axis gives us the SEASONS.
Effects of revolution and the tilt
The Earth's axis is tilted at about 23.5°. As the Earth revolves around the Sun, this tilt makes different parts receive the Sun's rays more directly at different times of the year. This causes the four seasons — spring, summer, autumn and winter — in temperate countries.
Example
In June the Northern Hemisphere tilts towards the Sun, giving it summer, while the Southern Hemisphere leans away and has winter.
Because Malaysia lies near the equator, it receives strong, near-vertical sunlight all year. It therefore has no four seasons — only a hot, wet equatorial climate with high temperatures and heavy rain throughout the year.
Remember
- Rotation → day and night (~24 hours).
- Revolution + 23.5° tilt → seasons (~365¼ days).
- Countries near the equator have little seasonal change.