In the conventional inverse square scheme, The Moon is exceptionally large relative to the Earth, being a quarter the diameter of the planet. and the Earth and Moon are still commonly considered a planet-satellite system instead of double planet According to Planet hypothesis of the moon, moon is planet and the mass known as earth,s is moon's From Angular mometum conservation, If we assume equivalent density for moon and earth, =2.626. then =3.656 Giga Meter If we assume existent distance and size for moon and earth, and high density for moon, Giga Meter which seems wrong values.