Objective
Students will understand how Earth’s tilt on its axis changes the length of daylight and
creates the seasons.
Reason Why We Have Seasons
23.5o
(Source: BBC - KS3 Bitesize Science)
It’s the tilt, Baby!
The Earth is tilted 23.5o. We have seasons because of the Earth’s tilt.
Position of Sun in the Sky Throughout the Year
Position of Sun – Summer Solstice (High in sky; direct sunlight)
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Objective
Students will understand how Earth’s tilt on its axis changes the length of daylight and
creates the seasons.
Position of Sun – Autumn Equinox (sunlight becoming indirect); Spring Equinox
(sunlight becoming more direct); Half-way between solstices.
Position of Sun – Winter Solstice (Low in sky; indirect sunlight)
(All three picture source: University of Wisconsin Milwaukee pantherFILE)
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Objective
Students will understand how Earth’s tilt on its axis changes the length of daylight and
creates the seasons.
Seasons Are Reversed in the Hemispheres
Date
Northern Hemisphere
Southern Hemisphere
June 21st – September 20th
Summer
Winter
September 21st – December 20th
Autumn
Spring
December 21st – March 20th
Winter
Summer
March 21st – June 20th
Spring
Autumn
Direct & Indirect Heat Energy From the Sun
Direct Heat Energy
The Sun is high in the sky.
The heat energy covers a
small area and is warmer.
Indirect Heat Energy
The Sun is
low in the
sky. The
heat energy
(we receive
the same
amount in summer and winter) covers a
large area and is cooler.
(Source: Morehead Planetarium UNC)
Seasons Vocabulary
Seasons - Due to the tilt of Earth as it travels around the Sun, we have spring,
summer, fall, and winter.
Earth’s Revolution - The circling of the Earth around the Sun. (The Moon also
revolves around the Earth.) It takes 365 days (one year) for the Earth to revolve
once around the Sun.
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Objective
Students will understand how Earth’s tilt on its axis changes the length of daylight and
creates the seasons.
Axis of Rotation - An imaginary line going from the North Pole to the South Pole.
The Earth spins on this line.
Earth’s Rotation – The Earth spinning on its axis. It takes the Earth 24 hours (one
day) to revolve one time around its axis.
Earth’s Tilt - The Earth’s axis is not straight up and down, instead it leans at a 23.5degree angle.
Orbit - The path that a planet travels as it goes around the Sun or a moon takes as it
goes around a planet.
Autumn
Summer
Winter
Spring
Direct Sunlight (heat energy) - Covers a small surface area; heat is concentrated
and warmer; Sun is high in the sky; summer heat energy is direct.
Indirect Sunlight (heat energy) - Covers a large surface area; heat is spread out and
colder; Sun is low in the sky; winter heat energy is indirect.
Summer
Direct Heat Energy
Winter
Indirect Heat Energy
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