Topic 9 – Exploring the Moon — Edexcel GCSE Astronomy
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Topic 9 – Exploring the Moon explained
Because the far side never faces Earth, it cannot be studied directly from Earth.
Read the full explanation
Information has been gathered mainly by spacecraft. Early Soviet Luna probes, especially Luna 3 in 1959, returned the first photographs of the far side. Later orbiters, landers and crewed missions have imaged and mapped it in detail. The Chang'e 4 mission achieved the first soft landing on the far side in 2019. Data come from visible-light cameras, radar, laser altimetry and other instruments on orbiters and landers. Radio communication with far-side spacecraft requires relay satellites because the Moon blocks direct signals from Earth. Learners should know these methods and why they were necessary.
Your focus
- Explain why the far side cannot be observed directly from Earth.
- Describe how spacecraft have gathered information about the far side, including named missions.
- State why radio relay satellites are needed for far-side communication.
Topic 9 – Exploring the Moon exam tips
Marking Points
- The far side cannot be observed directly from Earth because the Moon is tidally locked and always shows the same hemisphere to Earth.
- Spacecraft, including orbiters and landers, have been used to photograph and map the far side.
- Luna 3 in 1959 returned the first images of the lunar far side.
- Chang'e 4 achieved the first soft landing on the far side in 2019.
- Instruments such as cameras, radar and laser altimeters on spacecraft have collected data about far-side terrain.
- Radio relay satellites are needed to communicate with spacecraft on the far side because the Moon blocks direct radio signals from Earth.
Examiner Tips
- 💡Remember key firsts: Luna 3 first imaged the far side; Chang'e 4 first soft-landed there.
- 💡Link the method to the limitation: because Earth-based observation is impossible, spacecraft and relay satellites are used.
- 💡In multiple-choice questions, reject options that say the far side has never been seen or that it can be observed from Earth.
Common Mistakes
- Thinking the far side can be seen from Earth with telescopes: it never faces Earth, so spacecraft are required.
- Believing the far side is completely unexplored: it has been imaged and mapped by many spacecraft, and landed on by Chang'e 4.
- Forgetting the need for radio relays: direct communication from Earth to the far side is blocked by the Moon.
- Confusing the far side with the dark side: the far side is a fixed hemisphere, while the dark side depends on the Moon's phase.