Earth & space • Classes 9–12
The Moon changes its face. Why?
The Moon is not losing a piece every night.
Take your time. Speak, draw or write your answers.
Here is what is happening.
The Sun illuminates half of the Moon. As the Moon orbits Earth, we see different amounts of that illuminated half. This produces phases, repeating in about 29.5 days. Ordinary phases are not caused by Earth’s shadow; that is involved in a lunar eclipse.
Your little investigation
What you need
Paper, or NASA’s phase diagram below. Observe only from a safe place with an adult when needed. Never look at the Sun.
Draw the bright part of the Moon on three observation dates, if visible.
Record time and cloud cover; “not visible” is a valid observation.
Compare the sequence with NASA’s explanation. Separate observations from predictions.
What causes ordinary lunar phases?
KEEP ASKING
All activities in your group