Learn on PengiAmplify Science (California) Grade 5Chapter 2: Why is the sun up sometimes, but not other times?

Session 2: Earth's Spin (Rotation)

Key Idea.

Section 1

The Spinning Planet

Key Idea

Earth is never still. It is constantly spinning like a top. This spinning motion is called rotation.

Earth rotates around an imaginary line called an axis, which runs from the North Pole to the South Pole. It takes Earth about 24 hours to complete one full rotation. This daily spin is the clock that sets the rhythm of life on our planet.

Section 2

Creating Day and Night

Key Idea

This rotation is the engine behind day and night. Because Earth is a ball, the Sun can only shine on one half of it at a time.

As Earth rotates, different parts of the planet turn to face the Sun. When your location turns into the sunlight, you experience daytime. When your location turns away from the Sun and into Earth's shadow, you experience nighttime.

Section 3

Apparent Motion of the Sky

Key Idea

We don't feel Earth spinning, but we can see evidence of it. As Earth turns, the Sun and stars seem to move across the sky from east to west.

This is called apparent motion. The Sun isn't actually moving across the sky; Earth is spinning under it. Just like watching trees whiz by from a moving car, the sky looks like it is moving because we are moving.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

The Spinning Planet

Key Idea

Earth is never still. It is constantly spinning like a top. This spinning motion is called rotation.

Earth rotates around an imaginary line called an axis, which runs from the North Pole to the South Pole. It takes Earth about 24 hours to complete one full rotation. This daily spin is the clock that sets the rhythm of life on our planet.

Section 2

Creating Day and Night

Key Idea

This rotation is the engine behind day and night. Because Earth is a ball, the Sun can only shine on one half of it at a time.

As Earth rotates, different parts of the planet turn to face the Sun. When your location turns into the sunlight, you experience daytime. When your location turns away from the Sun and into Earth's shadow, you experience nighttime.

Section 3

Apparent Motion of the Sky

Key Idea

We don't feel Earth spinning, but we can see evidence of it. As Earth turns, the Sun and stars seem to move across the sky from east to west.

This is called apparent motion. The Sun isn't actually moving across the sky; Earth is spinning under it. Just like watching trees whiz by from a moving car, the sky looks like it is moving because we are moving.