Sometimes full, sometimes hidden or even invisible, here is the satellite of the Earth : the Moon.

 

     

     I am the Moon, THE satellite of the Earth.

We always see me on the same side because I spin round as fast as I rotate around the Earth.

 

 

 

    

I orbit  the Earth in 27 days.

The Earth orbits the sun : so I also orbit the Sun.

 

 

 

 

     During the new Moon, the sunbeams illuminate the face "hidden" of the Moon (the one facing the Sun) : from the Earth, we dont see it any more.

During the first and last quarter, the sunbeams illuminate half of the visible face (and half of the "hidden" face) : from Earth, we only see half of the Moon.

Finally during the full Moon, the sunbeams fully illuminate the visible face : from the Earth, the Moon is completely visible.