The Far Side

- Demonstrate an understanding of why the far side of the Moon is not visible from Earth
- Describe how astronomers know the appearance of the Moon's far side and how it differs from the near side

The Moon has a synchronous (or captured) rotation which means that from Earth only one side or hemisphere can be seen.

There is no expression in astronomy as "dark side of the Moon". The side we see is known as the near side. The side we cannot see is called the far side.

We can see up to 59% of the Moon's surface because of a process called libration. Sometimes we can see a little more of the poles and sometimes a fraction more of the east and western limbs depending on the Moon's and Earth's position.

We did not know what the far side looked like until the Soviet Luna 3 probe took pictures of it in 1959. Today the only humans to have viewed it are the Apollo astronauts.

The far side has fewer maria than the near side, it is more cratered. It is thought that the near side has a thinner crust and has had a higher amount of heat-producing elements.

No radio interference from Earth can reach the far side and so it is a candidate for a future radio telescope on the Moon.

 

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Questions

Describe why the rotation of the Moon allows us to only see one side of it.

Summary

  • We cannot see the far side of the Moon due to its synchronous rotation.
  • There is no "dark side" of the Moon. Both hemispheres receive equal amounts of sunlight.