Why does the Moon Change Shape?

When can we see the moon?

Waning moon
Waning moon
Waxing Moon
Waxing Moon

One side of the moon is always lit up by the sun but, it is not always visible to us. As the moon orbits Earth it goes through phases.

The phase of the moon is how much of the moon appears to be lit up by the sun while looking from here on Earth. A phase lasts about 28 days.

Within a phase if we can see all the moon’s lit up side, we call it a full moon. When we can’t see any of the lit up side, we call it a dark moon or new moon.  We cannot see the moon if it’s a new moon.

The Moon’s Phases.

As the moon orbits or circles the Earth, its phase changes.  The shape of the moon appears to change.  However, the moon is the moon, it’s just how much of the moon we see that is different.

The moon orbits Earth in an anti-clockwise path.  There are several phases, and so shapes, to pass through before a full cycle is complete.

Diagram showing Phases of the Moon
Diagram showing Phases of the Moon

The first phase is the New Moon phase. This is where we can’t see any of the lit up side of the moon. It is in shadow. The moon is between us and the sun.

As the moon orbits the Earth we gradually see more of the lit up side until finally the moon is on the opposite side of the Earth from the sun. We then see a full moon. As the moon continues to orbit the Earth we now see less and less of the lit up side.

A note to you and me.

Thanks for reading about my take on the phases of the moon.  I  hope you have enjoyed it.  If you have any info to add, if anything is clearly wrong or I have just missed the plot, please add a comment.  X

  1. I’m trying to get my head round the shadow.  If, for example when we see a crescent moon, is it that the lit side of the moon is in shadow? If it’s in shadow, where does the shadow come from?
  2. Why is it that we only see one side of the moon.  So, does the moon spin on itself as well as orbiting the Earth,
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