Seasons

Front

Axis Noun

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[ak-sis]

Back

Axis

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The imaginary line passing through the North and South poles, around which the Earth rotates at a 23.5-degree tilt.

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Example: This diagram shows Earth's axis, the imaginary tilted line it rotates on. This tilt is the primary reason we have different seasons throughout the year.

Front

Rotation Noun

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[roh-tey-shuhn]

Back

Rotation

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The spinning motion of an object on its own axis, which for Earth takes 24 hours and causes day and night.

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Example: This diagram shows the Earth's axis, the imaginary line it spins or 'rotates' on. This rotation is why one side has day and the other has night.

Front

Revolution Noun

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[rev-uh-loo-shuhn]

Back

Revolution

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The motion of one object moving in a path around another object, such as Earth's one-year journey around the Sun.

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Example: This diagram shows the Earth's revolution, its year-long orbit around the Sun. This movement, combined with the Earth's consistent tilt, causes the seasons.

Front

Orbit Noun

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[awr-bit]

Back

Orbit

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The specific, curved path that a celestial object, like a planet, takes as it revolves around another object, like the Sun.

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Example: This diagram shows Earth's elliptical orbit around the Sun, the curved path it follows. It highlights the closest (Perihelion) and farthest (Aphelion) points.

Front

Equator Noun

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[i-kwey-ter]

Back

Equator

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An imaginary line drawn horizontally around the middle of the Earth, dividing it into the Northern and Southern Hemispheres.

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Example: This diagram shows the Equator, an imaginary line around Earth's middle, receiving direct sunlight during an equinox, a key event in Earth's seasons.

Front

Hemisphere Noun

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[hem-i-sfeer]

Back

Hemisphere

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One half of the Earth, which is typically divided into the Northern and Southern halves by the equator.

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Example: The Earth is divided into halves called hemispheres. The Equator splits it into the Northern and Southern Hemispheres, which experience opposite seasons.

Front

Direct Sunlight Noun

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[di-rekt sun-lahyt]

Back

Direct Sunlight

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Sunlight that strikes Earth's surface at a high angle, concentrating solar energy and causing warmer temperatures in that area.

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Example: This diagram shows that direct sunlight is energy that travels in straight lines from the Sun and strikes the Earth, providing light and heat.

Front

Indirect Sunlight Noun

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[in-di-rekt sun-lahyt]

Back

Indirect Sunlight

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Sunlight that strikes Earth's surface at a low angle, spreading solar energy over a larger area and causing cooler temperatures.

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Example: This diagram shows that in winter, the sun follows a lower path in the sky, causing its light to be more spread out (indirect) and create long shadows.

Front

Solstice Noun

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[sol-stis]

Back

Solstice

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A time when a hemisphere is tilted most directly toward or away from the Sun, resulting in the year's longest or shortest day.

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Example: This diagram shows how Earth's tilted axis causes solstices; when a hemisphere is tilted most towards the Sun (summer) or away from it (winter).

Front

Equinox Noun

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[ee-kwi-noks]

Back

Equinox

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A time when neither hemisphere is tilted toward or away from the Sun, resulting in approximately 12 hours of daylight everywhere.

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Example: During an equinox, the Sun's rays shine directly on the equator, and the Earth's axis is not tilted, causing day and night to be nearly equal in length everywhere.