moon

The Moon orbits planet Earth and is Earth's only permanent natural satellite.

 

It is the fifth-largest natural satellite in the Solar System, and is thought to have formed about 4.51 billion years ago, not long after Earth.

 

Most people believe that the Moon formed from the remains of a giant crash between Earth and a massive meteor called Theia.

The Moon always shows the same side to earth. It is marked by dark areas caused by impact craters and light areas caused by  ancient crustal highlands, or mountains. 

 

After the Sun, the Moon is the second-brightest object in Earth's sky. Its surface is actually dark, although compared to the night sky it appears very bright. Its gravity produces the ocean tides and the slight lengthening of the day.

When the Moon covers the Sun in the sky it is called a total solar eclipse. These will not continue in the far future, because the Moon's distance from Earth is slowly increasing.