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Why do we always see the same side of the moon?

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Take a look at the moon and you'll always see the same 'face'. But surely the moon rotates on its axis? And what of this so-called 'dark side of the moon'.

I had to find an answer for this as it's the sort of thing that bugs my brain as I'm driving home at night.

The moon rotates. That is a fact. But it completes one rotation in pretty much the amount of time it takes to circle the Earth. Approximately 27.3 Earth days. 

The Earth completes one rotation on its axis every 24 hours. At least, that's how long it takes for our sun to appear at the exact same spot in the sky as viewed from a precise spot on Earth. This is a Solar Day. 

So, the Earth's rotation is quicker and depending on our moon's position relative to our position around the sun, the moon appears appropriately shadowed - the lunar cycle:

  • New Moon: The Moon is between the Earth and the Sun, and its illuminated side is facing away from the Earth, making it nearly invisible in the night sky.

  • Waxing Crescent: A sliver of the Moon becomes visible as it starts to move away from the alignment with the Sun, with a small crescent shape on the right side growing larger.

  • First Quarter: Half of the Moon's face is illuminated and visible from Earth. This phase is sometimes called a "half-moon" because we see one-half of the Moon's illuminated side.

  • Waxing Gibbous: More than half of the Moon is illuminated, and the visible portion continues to grow.

  • Full Moon: The entire face of the Moon that is facing Earth is fully illuminated by the Sun, appearing as a bright, round disk.

  • Waning Gibbous: The illuminated portion of the Moon begins to decrease, but more than half is still visible.

  • Last Quarter: Again, half of the Moon's face is illuminated, but this time the left half is visible. It is also called the "third quarter" phase.

  • Waning Crescent: The final sliver of the Moon's illuminated side is visible before it returns to the New Moon phase, completing the lunar cycle.

So, there is a dark side of the moon? Well, no. There is a far side of the moon which constantly faces away from us, but it recieves just as much light as the side that faces us. To imply that there is a perpetually darkened half of the moon is wrong.