earth axis

This geography lesson is designed for 6 to 12-year-old children to teach them about why Earth’s axis is tilted.

Why is the Earth’s Axis tilted?

The Giant Impact Hypothesis describes what happened around 4.5 billion years ago. At the time of the formation of the solar system, all the early forming planets were bombarded with stray material. An asteroid sized like Mars struck the young earth when it was still forming. In the aftermath, this is how the moon formed and the earth got its axial tilt.


What is an axial tilt?

In astronomy, the earth’s axis refers to the imaginary straight line passing from the North pole to the south pole on which the earth rotates. 

Whereas the earth’s orbital axis is the line perpendicular to the imaginary plane through which the earth moves as it rotates around the sun.

The earth axis tilt is the angle between the earth’s rotational axis and its orbital axis, which is a line perpendicular to its orbital plane. It is also called axial tilt or obliquity.

Over 41000 years, the earth’s obliquity oscillates between 22.1 and 24.5 degrees. Currently, the earth’s obliquity is about 23.4%.

Since the earth’s axis also wobbles, its obliquity angle also changes. This wobble motion is called axial precession, or the precession of the equinoxes, and is caused by the gravitational force of the Sun, the Moon, and other planets. 


Earth’s Obliquity or Axial Tilt Causes Seasons

As the earth orbits the sun at an angle, the amount of solar energy reaching different parts of our planet varies over a year.

As a result, we have different seasons and the seasons are opposite in the north and south hemispheres. This video will give a glimpse of the solstices which occur twice annually.

Furthermore, the video lesson teaches the child how the planet earth revolves around the sun and what causes the length of the day and night to vary. 

Watch the video to learn about the earth’s axis tilt using a practical illustration.


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Video Created by: Justine McNeilly.