Sometimes white, sometimes red, crescent-shaped, oval or perfectly round, the Moon has been the faithful companion of the Earth for billions of years.
Born at the same time as the Earth, the Night Lady has aged prematurely but her gaze has kept its intensity and still makes many dreamers dream who woo her when she deigns to appear above the horizon.
The Moon is not a planet because it does not revolve around the Sun; the moon revolves around the Earth. It is therefore the natural satellite of the Earth. But there are also so-called artificial satellites that revolve around the Earth and are used for telecommunications or to study our planet.
The Moon orbits very far from the Earth, at about 384000 km distance while most artificial satellites revolve around the Earth at about 500 km altitude, some at 36000 km like geostationary satellites.
The Moon is so far that it takes 4 days to reach it by rocket. We'll talk about it in the page dedicated to the exploration of the Moon.
The Moon always has the same apparent diameter, even near the horizon where it looks much bigger. It is actually an optical illusion as seen in the photograph shown on the left: near the horizon or very high in the sky the Moon always has the same diameter!
Four times smaller and 81 times lighter than Earth, the Moon is 3476 km in diameter. It is one of the largest satellites in the solar system, as large as the Jupiter-based Europe satellite, which you can observe as a bright star in a small telescope.
It represents 3/4 of the planet Mercury which is the closest planet to the Sun.