What does Edexcel GCSE Astronomy Topic 9 cover?

Topic 9 covers the Moon's major internal divisions compared with the Earth's, the differences between the near and far sides, how information about the far side was gathered, that a spacecraft must reach escape velocity (achievable only with rockets), and the theories of the Moon's origin (the Giant Impact Hypothesis, Capture Theory and Co-accretion Theory).

How does the far side of the Moon differ from the near side?

The far side has far fewer maria (dark plains) than the near side, so it appears lighter and much more heavily cratered, and its crust is thicker. The far side can never be seen from Earth because synchronous rotation keeps it turned away, so it was first mapped by spacecraft (beginning with Luna 3 in 1959).

What is the Giant Impact Hypothesis?

The Giant Impact Hypothesis is the favoured theory of the Moon's origin: early in the Solar System's history, a Mars-sized body collided with the young Earth, throwing debris into orbit, which accreted under gravity to form the Moon. It best explains the Moon's small iron core and the similarity of Earth and Moon rocks.

Why must a spacecraft reach escape velocity to reach the Moon?

To leave the Earth and travel to the Moon, a spacecraft must reach the Earth's escape velocity, the minimum speed to escape the Earth's gravity. This needs a very large amount of energy, which can only be supplied by rockets, so crewed lunar missions require enormous multi-stage rockets.

How should I revise Topic 9 for Edexcel GCSE Astronomy?

Compare the Moon's structure with the Earth's (smaller core, thicker crust), learn the near and far side differences and that the far side was mapped by spacecraft because synchronous rotation hides it, and know the three origin theories with the Giant Impact as the favoured one. Remember the far side is hidden, not unlit, and that rockets are needed for escape velocity.

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Edexcel GCSE Astronomy Topic 9 Exploring the Moon: a complete overview of the Moon's structure, far side, escape velocity and origin

A deep-dive Edexcel GCSE Astronomy guide to Topic 9 Exploring the Moon. Covers the Moon's internal structure compared with the Earth's, the near and far sides, escape velocity and the need for rockets, and the theories of the Moon's origin, with the exam patterns Pearson repeats.

Generated by Claude Opus 4.811 min read1AS0 Topic 9Updated 2026-06-02

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What Topic 9 actually demands
Structure, the far side and origin
How Topic 9 is examined
Check your knowledge

What Topic 9 actually demands

Exploring the Moon opens Paper 2 (telescopic astronomy) with the Moon's interior, far side, and origin. It rewards comparison (the Moon versus the Earth, the near versus far side) and clear description of the origin theories.

This guide walks through the single dot point of the topic, then sets out the exam patterns Pearson repeats. The dot point has a matching page with practice questions; this overview ties them together.

Structure, the far side and origin

The Moon has a crust, mantle and core like the Earth, but a much smaller core and a thicker crust. The far side has far fewer maria (so it is more cratered) and a thicker crust, and is hidden by synchronous rotation, first mapped by spacecraft. Reaching the Moon needs escape velocity, achievable only with rockets. The favoured origin is the Giant Impact Hypothesis (a Mars-sized body hit the early Earth; the debris formed the Moon); alternatives are Capture and Co-accretion.

How Topic 9 is examined

A typical Edexcel profile for exploring the Moon:

Comparison. The Moon's structure versus the Earth's, and the near versus far side.
Explanation. Why the far side is hidden and how it was mapped.
Description. The Giant Impact Hypothesis and the alternatives.
Recall. Escape velocity and the need for rockets.

Check your knowledge

A mix of comparison and description questions covering Topic 9. Attempt them under timed conditions, then check against the solutions.

State one way the Moon's internal structure differs from the Earth's. (1 mark)
State two ways the far side of the Moon differs from the near side. (2 marks)
Explain why the far side of the Moon was unknown until spacecraft were sent. (2 marks)
State why a spacecraft must reach escape velocity to leave the Earth. (1 mark)
Describe the Giant Impact Hypothesis. (2 marks)
Name one alternative theory of the Moon's origin. (1 mark)
State which theory of the Moon's origin is currently favoured. (1 mark)

Sources & how we know this

Pearson Edexcel Level 1/Level 2 GCSE (9-1) in Astronomy (1AS0) specification — Pearson (2017)