The Moon

The Earth's only satellite is a sphere of rock of about 3,476 km in diameter (our planet is about 12,700 km in diameter, so it is about four times smaller than the Earth). There is no air or atmosphere on the Moon because its gravity ins’t strong enough. The temperature on the Moon varies from -153 degrees at night to 123 degrees during the day. The Moon’s surface is rocky and has craters and mountains. These craters are caused when meteorites hit the surface of the Moon. We can observe these countless craters because the Moon has no atmosphere. There is also no wind or rain on the Moon to erode them.

The Moon rotates on its axis, which takes 29.5 days.

Its orbit around the Earth also takes 29.5 days. Because of this, we always see the same side of the Moon. The Moon does not produce its own light. We can see the Moon because it reflects sunlight. Obviously, we can only see the illuminated part that is facing the Earth. This is why when we look at the Moon on different nights during the lunar month, its shape changes. These different shapes are called the phases of the Moon.

Because the Moon is very big and quite close to the Earth, it produces certain effects on our planet:

- It causes eclipses, which can be total or partial, when it is between the Earth and the Sun.

- It causes tides, which are the rising and falling of the level of the sea. This happens about every six hours.