The Moon Guide
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The phase of the Moon right now

Phase
 
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< Moon rocks on Earth
As well as impact events, the Moon is also rocked by ‘moonquakes’, the lunar equivalent of earthquakes. There are four different types of moonquake. Deep moonquakes occur up to 700 kilometres below the Moon’s surface and are a result of tidal stresses caused by the gravitational tug of war between the Earth, Moon and Sun. Shallow moonquakes occur at the surface and down to depths less than about 20 or 30 kilometres, and are often due to landslides of rock down steep crater rims. The Moon also suffers from thermal moonquakes, which occur when the freezing crust expands as it returns into sunlight after two weeks of lunar night time. Meteorite moonquakes can also cause a rumble or vibration of the surface when a meteroid slams into the surface.

Moonquakes are much less common than earthquakes and, apart from the shallow quakes, are also much weaker than the killer earthquakes we have experienced on Earth. Experiments conducted by the Apollo astronauts measured shallow moonquakes reaching the equivalent of 5.5 on the Richter scale, with surface vibration occurring for many minutes longer than on the Earth, which would cause damage to buildings on the Earth. Future lunar settlers will have to be careful that they build strong enough houses and observatories for their telescopes to withstand these shallow moonquakes.

lunar seismometer
The lunar seismometer (lower right) carried aboard Apollo 16.

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Geologist on the Moon

Lunar geology

Moon rocks on Earth

Moon quakes

How the Moon was formed

Geology of the Moon's features

What is the Moon made of?

Lunar gardening

About impacts

Ray craters

Ageing wrinkles

Meandering channels

 
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