Earth’s Seasons

The Reason for the

Seasons

Earth’s Changing Seasons
Earth experiences four distinct seasons: spring, summer, autumn, and winter. These
changes are primarily caused by two factors: the tilt of Earth’s axis and its revolution around
the Sun.

Tilt of Earth’s Axis

Earth’s axis is an imaginary line that runs from the North Pole to the South Pole. This axis is
tilted at an angle of about 23.5 degrees. Because of this tilt, different parts of Earth receive
varying amounts of sunlight throughout the year.

Revolution Around the Sun

Earth takes about 365 days to complete one orbit around the Sun. As Earth revolves, the tilt
of its axis causes different hemispheres to receive more direct sunlight at different times of
the year. For instance, during summer in the Northern Hemisphere, the North Pole is tilted
toward the Sun, resulting in longer days and warmer temperatures. Conversely, during
winter, the North Pole is tilted away from the Sun, leading to shorter days and cooler
temperatures.

Critical Thinking Question
How might the changing seasons affect the behavior of animals and plants in different
regions of the world? Consider how their adaptations to these seasonal changes might
differ between polar regions and tropical regions.

The Earth moves in two different ways in space.

The Earth rotates and revolves.

Earth’s Movement

Revolution

(orbit)

365.25 days

Rotation (spin)

24 hours

Turn and Talk

What is the difference between
rotate and revolve?

Multiple Choice

Select your answer below:

• A

• B

• C

• D

Multiple Choice

Select your answer below:

• A

• B

• C

• D

The seasons have a lot of impact on what happens on the earth. 

In the spring, animals are born and plants come back to life. 

Summer is hot and is when kids are usually out of school and we take vacations to the beach. Often crops are harvested at the end of the summer. 

In autumn the leaves change colors and fall off the trees and school starts again. 

Winter is cold and it snows in many places. Some animals, like bears, hibernate in the winter while other animals, like birds, migrate to warmer climates.

Open Ended

Compare and contrast the different seasons that we experience on Earth. Which season do you believe to be the most important season for Earth? Explain your reasoning.

What Causes Seasons?

Seasons are caused because of the Earth's changing relationship to the Sun. 

The Earth travels around the Sun, called an orbit, once a year or every 365 days. 

As the Earth orbits the Sun, the amount of sunlight each location on the planet gets every day changes slightly. 

This change causes the seasons.

Multiple Choice

What causes the seasons on Earth?

• The distance from the Sun

• The tilt of Earth’s axis and its revolution around the Sun

• The phases of the Moon

• The rotation of Earth on its axis

Earth’s Tilt

​Not only does the Earth revolve around the Sun every year, but the Earth rotates on its axis every 24 hours. 
This is what we call a day. 

However, the Earth doesn't rotate in a straight up and down manner relative to the Sun. 

It is slightly tilted. In scientific terms, the Earth is tilted 23.5 degrees from its orbital plane with the Sun.

Earth’s Tilt

​The tilt has two major effects: the angle of the Sun to the earth and length of the days. 

For half of the year the Earth is tilted such that the North Pole is more pointed towards the Sun. 

For the other half the South Pole is pointed at the Sun. 

When the North Pole is angled toward the Sun, the days on the northern part of the planet (north of the equator) get more sunlight or longer days and shorter nights. 

​Response Cards

​What are the two major effects of Earth’s tilt? Compare and contrast the effects of Earth’s tilt on different regions of the planet, for example the Northern Hemisphere vs the Souther Hemisphere.

With longer days the northern hemisphere heats up and gets summer. 

As the year progresses, the Earth's tilt changes to where the North Pole is pointing away from the Sun producing winter. 

For this reason, seasons north of the Equator are the opposite of seasons south of the Equator. 

When it's winter in Europe and the United States, it will be summer in Brazil and Australia. 

In summer the sunlight shines more directly on the earth giving more energy to the Earth's surface and heating it up. 

During the winter the sunlight hits the Earth at an angle. This gives less energy and doesn't heat the Earth as much.

Multiple Choice

How does the tilt of Earth’s axis affect temperatures in different seasons?

• It does not affect temperatures at all

• It causes temperatures to remain constant

• It affects how much direct sunlight parts of the planet receive

• All parts of the Earth receive the same sunlight and the same temperatures all year.

Fill in the Blank

Use your response cards to complete the statements

,

,

,

,

Select the Facts!

A. When the northern hemisphere of the Earth is tilted

away from the Sun, people in
the these
regions are experiencing winter.

B. The earth rotates on its axis
C. An axis is when a celestial body is rotating on its

side

D. The moon is the reason for the seasons changing
E. The seasons change because Earth rotates on its

axis and some areas point towards the sun while
the other side points away from the sun.