What Causes Seasons?

What Causes Seasons?

There are two main reasons for the season to change every few months

• The Earth’s tilted axis
• The Earth revolving around the Sun

Earth’s Tilted Axis

We need to think about two imaginary lines when we talk about our Earth

Axis

The Earth is a sphere with two poles – the North Pole and the South Pole

The axis is an imaginary line that passes through the two poles. This is, however not a straight line. It is tilted at an angle.

Equator

The equator is an imaginary line that divides the Earth into two hemispheres, the Northern Hemisphere and the Southern Hemisphere.

Earth’s Revolution

The Earth, on its tilted axis, revolves around the Sun on an elliptical (like an oval) path. It takes an entire year (365 days) to complete one revolution.

• As the Earth revolves around the Sun, the tilt of its axis causes different parts of the Earth to be closer to the Sun or away from it. 
• Each part receives a different amount of sunlight and heat, causing the four seasons.
• The four seasons are reversed in the Northern and Southern Hemisphere as they are tilted towards the sun at different times of the year. 

Example: When it is summer in the USA, which is in the Northern Hemisphere, it is winter in Australia, which is in the Southern Hemisphere.