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LessonsCatch the Flaw

Lesson 18 · Science · Models of the Moon

Step 1 of 4

Find the wrong step

A child comparing Moon phases with a Sun and Moon model
Your lessonModels of the MoonCore

The Moon-Phase Shadow File

Over a month, observers see the Moon look crescent, half-lit, full, and then thin again.

Light source
The Sun
Changing view
The Moon orbits Earth

Your question

Why do the Moon's phases change?

Lumi’s answer: “Earth's shadow covers a different part of the Moon every night.”

1

Step 1 of 4

Find the wrong step

Find where the reasoning first breaks

Start with Step 1 and move downward. Choose the first line that stops making sense.

Later lines may be wrong too. Pick the first mistake.

Lumi’s work

These lines form one solution. Read them from top to bottom.

  1. 1

    The Moon does not make its own visible light. Sunlight illuminates it.

  2. 2

    Sunlight always illuminates half of the Moon.

  3. 3

    As the Moon orbits Earth, our view of that sunlit half changes.

  4. 4

    Therefore every Moon phase is caused by Earth's shadow.