Seasons

Seasons

Middle School

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Learning Objectives

• Define what seasons are and describe the four distinct times of the year.

• Explain how the tilt of the Earth's axis and its revolution cause the seasons.

• Differentiate between solstices and equinoxes and the conditions they create.

• Understand why the Northern and Southern Hemispheres experience opposite seasons.

Key Vocabulary

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Axis

An imaginary line through the north and south poles on which our planet Earth rotates.

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Revolution

The motion of an object, like Earth, as it travels in an orbit around another object.

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Rotation

The spinning motion of an object on its own axis. Earth's rotation causes day and night.

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Solstice

The time a hemisphere gets the most or least direct sunlight, marking summer or winter's start.

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Equinox

The time when both of Earth's hemispheres receive an equal amount of direct sunlight from the Sun.

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Earth's Movement: Rotation and Revolution

Rotation

• ​The Earth spins on an imaginary line called an axis.

• ​​This rotation takes 24 hours to complete and causes day and night.

• ​When part of the Earth faces the Sun, it is day; when it faces away, it is night.

Revolution

• ​The Earth moves around the Sun in a fixed path called an orbit.

• ​​This journey, known as a revolution, takes about one year to complete.

• ​This movement is a key reason we experience different seasons during the year.

Multiple Choice

Which statement accurately describes Earth's movements?

• Earth's rotation on its axis causes the seasons.

• Earth's revolution around the Sun causes day and night.

• Earth's rotation takes one year, and its revolution takes 24 hours.

• Earth's rotation causes day and night, and its revolution causes the year.

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Earth's Tilt: The Reason for Seasons

• The equator divides the Earth into Northern and Southern Hemispheres.

• The primary cause of seasons is the 23.5-degree tilt of Earth’s axis.

• This tilt causes parts of Earth to receive sunlight at different angles.

• Direct sunlight is more intense and causes warmer weather than indirect sunlight.

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Multiple Choice

What is the main reason for the change in seasons?

• The Earth's distance from the Sun changes.

• The Earth's axis is tilted at 23.5 degrees.

• The Earth rotates on its axis every 24 hours.

• The Sun gives off different amounts of heat.

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The Extremes: Summer and Winter Solstices

Summer Solstice (June)

• The Northern Hemisphere is tilted toward the Sun, receiving more direct sunlight.

• This results in the longest day of the year and warmer temperatures.

• During this time, the Southern Hemisphere experiences its winter season.

Winter Solstice (Dec)

• The Northern Hemisphere is tilted away from the Sun, receiving less direct sunlight.

• This results in the shortest day of the year and cooler temperatures.

• During this time, the Southern Hemisphere experiences its summer season.

Multiple Choice

When it is summer in the Northern Hemisphere, what season is it in the Southern Hemisphere?

• Summer

• Winter

• Spring

• Fall

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The Balance: Spring and Fall Equinoxes

What is an Equinox?

• An equinox happens when the Sun's direct rays shine on the equator.

• During this time, neither hemisphere is tilted toward or away from the Sun.

• This results in nearly 12 hours of daylight and 12 hours of nighttime.

The Two Equinoxes

• The Vernal Equinox marks the beginning of spring in the Northern Hemisphere.

• The Autumnal Equinox marks the start of fall in the Northern Hemisphere.

• The seasons are always opposite in the Northern and Southern Hemispheres.

Multiple Choice

What is a key feature of an equinox?

• One hemisphere receives much more direct sunlight than the other.

• It marks the longest or shortest day of the year.

• Day and night are approximately equal in length.

• The Earth's axis is not tilted during an equinox.

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Common Misconceptions About Seasons

Misconception	Correction
Earth's distance from the Sun causes the seasons.	The 23.5-degree tilt of Earth's axis is the cause of the seasons.
The Sun releases more heat during the summer.	The Sun's energy output is stable throughout the year.
The same season happens everywhere at once.	Hemispheres have opposite seasons, like summer and winter.

Multiple Choice

Why is it warmer in the summer in the Northern Hemisphere?

• The Earth is closer to the Sun during the summer.

• The Northern Hemisphere is tilted toward the Sun, receiving more direct sunlight.

• The Earth's rotation speeds up in the summer.

• The Sun produces more heat during the summer months.

Multiple Choice

If the Earth's axis had no tilt, what would be the most likely effect on the seasons?

• The seasons would be much more extreme.

• There would be no significant seasons, just one year-round climate.

• The Northern Hemisphere would be in permanent summer.

• The length of a day would be much longer than 24 hours.

Multiple Choice

A student in Argentina (Southern Hemisphere) notices the days are getting longer and the weather is getting warmer in November. What is happening to the Earth's tilt, and what season is a student in the United States (Northern Hemisphere) likely experiencing?

• The Southern Hemisphere is tilting toward the Sun; the US is experiencing Spring.

• The Southern Hemisphere is tilting toward the Sun; the US is experiencing Fall.

• The Southern Hemisphere is tilting away from the Sun; the US is experiencing Summer.

• The Earth's tilt is neutral; the US is experiencing Winter.

Multiple Choice

How would a decrease in Earth's axial tilt, from 23.5 to 15 degrees, most likely influence the seasons?

• It would make summers hotter and winters colder.

• It would eliminate the seasons entirely.

• It would result in milder seasons, with cooler summers and warmer winters.

• It would reverse the seasons in each hemisphere.

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Summary

• Earth's 23.5-degree tilt and revolution cause seasons; rotation causes day and night.

• A hemisphere tilted toward the Sun has summer; one tilted away has winter.

• During an equinox, neither hemisphere is tilted, causing nearly equal day and night.

• The Northern and Southern Hemispheres always experience opposite seasons.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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