Meaning of Rotation
Rotation: The spinning movement of the Earth on its own imaginary axis.
Axis: An imaginary straight line through the Earth from the North Pole to the South Pole.
Properties of Earth’s Rotation
Property Description
Axis Imaginary line through North and South Poles
Direction West → East (counter-clockwise if viewed from above North Pole)
Speed About 1,670 km/h at the equator (fast, but we don’t feel it)
Time 24 hours (1 solar day)
Inclination Axis is tilted at 23.5° (causes seasons, but rotation itself gives day/night)
Causes of Day and Night:
· The Earth is spherical.
· The Sun lights only one half at a time.
· Rotation moves places in and out of sunlight.
Effects of Earth’s Rotation (8 minutes)
Four Major Effects of Earth’s Rotation:
1. Day and Night – The most direct effect.
2. Apparent movement of the Sun – Sun appears to rise in the East and set in the West (actually the Earth is moving).
3. Deflection of winds and ocean currents – Due to the Coriolis Effect:
· Winds curve to the right in the Northern Hemisphere.
· Winds curve to the left in the Southern Hemisphere.
· This affects weather patterns and ocean currents.
4. Difference in time across longitudes – Causes time zones (e.g., when it is 12:00 noon in Nigeria, it is early morning in New York).
Additional effect: Slight bulging at the equator (centrifugal force from spinning).
Rotation vs. Revolution
Feature Rotation Revolution
Movement Spinning on axis Moving around Sun
Time 24 hours 365¼ days
Causes Day & Night Seasons
Path Stationary axis Orbit (ellipse)
