Figure 6.19 The Moon's surface as seen by Apollo astronauts. (Photo: NASA)


The Moon has no real atmosphere and no liquid water. Atmospheres are held in place by gravity, and the Moon has so little gravitational pull that it is unable to hold any of the gases such as those that make up the Earth's atmosphere.


There is a large range of temperatures on the surface of the Moon because of its lack of atmosphere. On the night side temperatures can fall to

-184°C, while on the parts of the Moon facing the Sun temperatures can reach 130°C. At the poles, temperatures are constantly low, about -96°C. Some polar regions are in permanent shadow.

Because the Moon rotates once on its axis every 27.3 days, night and day at any point on the Moon last about fourteen Earth days. On the side of the Moon that always faces Earth, 'phases of the Earth' would be observed. Part of the long period of night would be 'Earth-lit', just as we have 'Moonlit' nights on Earth.

Magnetic field

The Moon has no global magnetic field, but some rocks brought back by the Apollo astronauts exhibit permanent magnetism. This suggests that there may have been a global magnetic field early in the Moon's history.

With no atmosphere and no magnetic field, the Moon's surface is directly exposed to the solar wind. Since the Moon's early days, many charged particles from the solar wind would have become embedded in the Moon's regolith (surface material). Samples of regolith returned by the Apollo astronauts confirmed the presence of these charged particles.

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