<Tr> <Th> Composition by volume </Th> <Td> <Ul> <Li> He </Li> <Li> Ar </Li> <Li> Ne </Li> <Li> Na </Li> <Li> </Li> <Li> </Li> <Li> Rn </Li> </Ul> </Td> </Tr> <Ul> <Li> He </Li> <Li> Ar </Li> <Li> Ne </Li> <Li> Na </Li> <Li> </Li> <Li> </Li> <Li> Rn </Li> </Ul> <P> The Moon is an astronomical body that orbits planet Earth, being Earth's only permanent natural satellite . It is the fifth - largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits (its primary). Following Jupiter's satellite Io, the Moon is second - densest satellite among those whose densities are known . </P> <P> The Moon is thought to have formed about 4.51 billion years ago, not long after Earth . The most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars - sized body called Theia . </P>

What is the name of the moon on earth