Lesson 3 of 10
Waxing and waning
Show on a big screenTonight the Moon is a thin curve. Is the bright part growing, or shrinking?
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Step 1 of 4
- New Moon, Amavasya: none of the lit half faces us.
- Next, the bright part grows. This is waxing.
- Full Moon, Purnima: all of the lit half faces us.
- Then the bright part shrinks. This is waning.
The rule
Both, one after the other. It grows for about 15 days. Then it shrinks for about 15 days.
From New Moon to Full Moon, the bright part grows. This is waxing.
From Full Moon to the next New Moon, the bright part shrinks. This is waning.
In India, New Moon night is Amavasya. Full Moon night is Purnima.
A quarter Moon is a quarter of the orbit from New Moon. We see half the disc bright.
Watch out!
The Moon does not grow. Only the bright part we can see grows or shrinks.
Try the lab to finish this lesson.