The Moon

Topic 2 – The Lunar Disc

2.1 - Know the shape of the Moon

2.2 - Be able to use information about the mean diameter of the Moon (3500 km)

2.3 - Be able to recognise the appearance of the principal naked-eye lunar surface formations, including:
a - craters
b - maria
c - terrae
d - mountains
e - valleys

2.4 - Understand the structure and origin of the principal naked-eye lunar surface formations, including:
a - craters
b - maria
c - terrae
d - mountains
e - valleys

2.5 - Be able to identify the following features on the lunar disc:
a - Sea of Tranquility
b - Ocean of Storms
c - Sea of Crises
d - Tycho
e - Copernicus
f - Kepler
g - Apennine mountain range

2.6 - Be able to use the rotation and revolution (orbital) periods of the Moon

2.7 - Understand the synchronous nature of the Moon’s orbit

2.8 - Understand the causes of lunar libration and its effect on the visibility of the lunar disc

Topic 3 – The Earth-Moon-Sun system

3.5 - Understand the relative effects of the Sun and Moon in producing high and low, spring and neap tides

Topic 4 – Time and the Earth-Moon-Sun cycles

4.9 - Understand the lunar phase cycle

Topic 9 – Exploring the Moon

9.1 - Understand the Moon’s major internal divisions in comparison with those of the Earth

9.2 - Understand the major differences between the appearance of the Moon’s near and far sides

9.3 - Understand how information has been gathered about the Moon's far side

9.5 - Understand the Giant Impact Hypothesis and alternative theories of the Moon’s origin, including Capture Theory and Co-accretion Theory

See the Phases, Apollo and Rocket pages for more information on those parts of the specification


Humanity has long been fascinated by the Moon. It affects our tides on Earth and in the past has influenced our calender (the word "month" comes from the word "moon").

The Moon is not a planet but a satellite of Earth's, our only natural one.

Some astronomers class the Earth and Moon as a double planet as other planets have moons that are substantially smaller than ours (with the exception of Pluto).

There is no atmosphere on the Moon. It may have had one at some point but its gravity was too weak to keep hold of it. Astronauts measured moon quakes during their visits but these are mild compared to Earth's and are caused by the tidal forces of our planet. Solar wind and the extreme hot and cold temperatures may have an erosive effect on the surface but otherwise scientists consider the Moon to be a dead world.

In this section you will learn about the Moon's size, orbit, features, phases, gravity and mass.

Lunar Lingo

Some terms to help you in this section:

  • Face: The part of the moon that we see
  • Limb: The edge of the moon
  • Terminator: The division between light and dark (night and day) on the moon.

At the end of this section take the mini quiz to test yourself.


Current Moon Phase