The Moon is Earth’s only natural satellite and was formed 4.6 billion years ago around some 30–50 million years after the formation of the solar system. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth. The fifth largest moon in the solar system, Earth's moon is the only place beyond Earth where humans have set foot.
Page Updated: September 25, 2018
What is the moon made of, and how did it form? Learn about the moon's violent origins, how its phases shaped the earliest calendars, and how humans first explored Earth's only natural satellite half a century ago.
Source: National Geographic (Youtube) Published: on July 26, 2018
Animation of the Moon as it cycles through its phases, as seen from the Southern Hemisphere in 2007. The apparent wobbling of the Moon is known as libration. The gradual change in apparent size is due to the eccentricity of the lunar orbit. (North is down.)