Moon
The Earth and Mars are the only planets interiors that have satellites, and the moon is the only natural satellite having the Earth.
It seems that the Moon was formed when a hypothetical planet, called Theia, violently impacted the Earth about 4.5 billion years ago, and a large amount of these materials were grouped together by gravity to form our only satellite.
It is a fairly large satellite, it is the largest in the Solar System in relation to its planet, which causes a great gravitational attraction that causes the tides.
It takes 28 days to go around the Earth, exactly the same as to turn on itself, so its translation lasts the same as its rotation. This means that it always shows the same face towards the Earth and we never see the opposite face ("the hidden face of the Moon").
Although the Moon illuminates the nights of the Earth, its brightness comes from the reflection of sunlight on its surface.
The Moon does not have an atmosphere, so the craters produced by the impacts of meteorites that have collided with its surface can still be seen. From the Earth, some flat and dark areas called seas are distinguished among other brighter mountainous areas.
Since the Moon is very close to the Earth, it appears to be the same size as the Sun and can even block the Sun's light in total solar eclipses.
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