This drawing illustrates how forming moons drew gas to themselves.
Image from: The New Solar System
The Co-Formation Theory
The co-formation theory explains the origin of the moon as an object which formed out of the
primitive solar nebula at the same time and roughly the same place as the Earth. As shown in this picture, while they were forming in the solar nebula, the nucleii of the moons-to-be (called protomoons)
drew material to themselves from the cloud of gas and dust around them.
Because the proto-moon was so close to the proto-earth the nebular material out of which they both formed ought to be very similar, composed mostly of rocky material rather than volatile gases.
The co-formation theory explains why the moon appears in the location it does but it does not explain the evidence that the Earth and Moon do not appear to be made of the same material.
You might also be interested in:

The position of the planets in the solar nebula greatly affected their 1. size and 2. composition. This is because of the effect of how cold it was in the nebula. 1. The nebula was a lot warmer close to
...more
As shown in this picture, while they were forming in the solar nebula, the nucleii of the planets-to-be (called protoplanets) drew material to themselves from the cloud of gas and dust around them. The
...more
The co-formation theory explains the origin of the moon as an object which formed out of the primitive solar nebula at the same time and roughly the same place as the Earth. As shown in this picture, while
...more
In decades past it was accepted that moons such as the Earth's moon or the moons of Jupiter were airless bodies with no atmosphere whatsoever. Now, however, measurements have shown that most of these moons
...more
Unlike the Earth, which has a protective shield around it called the magnetosphere, the surface of the moon is not protected from the solar wind. This picture shows the magnetosphere surrounding the Earth,
...more
You may have heard people refer to a Full Moon in the autumn as the "Harvest Moon" or the "Hunter's Moon". Native Americans in the eastern and northern parts of North America had special names for the
...more
Altocumulus clouds (weather symbol - Ac), are made primarily of liquid water and have a thickness of 1 km. They are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part
...more