The moon is not bigger than the Earth as it has a diameter of approximately 2,159 square miles, which is about one-quarter of the size of Earth. In addition to being smaller than the Earth, the moon is much lighter. It weighs approximately 80 times less than Earth, but what it lacks in density, the moon makes up for in luminosity.
The moon orbits the Earth in a continuous circular orbital pattern. It circles the moon on a monthly basis, and its path across the sky can be observed in several phases, including the new moon and full moon. The moon circles the Earth on a predetermined path and is kept in orbit by the forces of gravity. As the moon progresses across the sky, the angles between it, the sun and the Earth change. This change in angle creates the various phases of the lunar cycle. Although the moon is small in comparison to Earth, it is considered to be a relatively large celestial body in comparison to other planets in the solar system. Its size makes the moon classifiable as a terrestrial planet, which is a category shared by Mars, Mercury and Venus. The moon was first visited by astronauts in 1959 when the Soviet Union successfully landed the Luna 2 on the surface of the moon.