[SunkenCiv]

Okay, there is at least one advocate of coaccretion:

Did the new moon lose its iron heart?
New Scientist
January 23, 2007

The current theory says that the material that now forms our moon was ejected when Earth was struck by another planet-sized body. But Peter Noerdlinger at Saint Mary's University in Halifax, Canada, says this theory has problems. "The collision has to be implausibly gentle. You practically need someone to hold a Mars-sized object just above Earth and drop it, to avoid messing up Earth's orbit."

The simpler idea that Earth and the moon were both created from the same gas cloud had been rejected because it could not explain why Earth formed an iron core and the moon did not. Now, Noerdlinger has an answer for that.

He suggests that the proto-moon did have an iron core, but that the satellite was ripped apart in a close encounter with Earth. His calculations show that iron from the core would be pulled towards Earth, while the remains of its rocky outer shell reassembled into our iron-free moon.

This fits with evidence that the Earth acquired a veneer of iron after it formed, Noerdlinger says. He presented the work at the American Astronomical Society meeting in Seattle, Washington, last week.

From issue 2587 of New Scientist magazine, 23 January 2007, page 16

[SunkenCiv]

Chinese Scientist Gives New Hypothesis on Origin of the Moon
People's Daily
Thursday, November 29, 2001

A planet collision may have helped form the Moon. This is the new hypothesis on the origin of the Moon by Huang Jinzhong, a geographer from the Seismology Bureau of Quanzhou City. Huang said two planets, between the orbits of Mars and Jupiter, collided and split some 4.6 billion years ago, and one of the fragments formed rudiments of the Moon. Huang supported his hypothesis with evidence of the Moon's internal structure and chemical components, the age of rocks on the Moon, and other geological data. A planet collision may have helped form the Moon. This is the new hypothesis on the origin of the Moon by Huang Jinzhong, a geographer from the Seismology Bureau of Quanzhou City, Fujian Province, according to latest issue of Beijing Review.

Rudiments of the Moon Comes From Fragments

In a paper submitted to the annual meeting of the China Association for Science and Technology (CAST), Huang said two planets, between the orbits of Mars and Jupiter, collided and split some 4.6 billion years ago, and one of the fragments formed rudiments of the Moon.

This rudiment Moon was a melting celestial body, circling the Sun, according to Huang. Influenced by Jupiter's gravitation, its orbit began to change. The rudiment Moon collided with the South Pole region of the Earth some 4.46 billion years ago, and rebounded from it. The rebound force and Earth's centrifugal force then caused the Moon to circle around the Earth, he said.

Evidence from Structure & Chemical Components

Huang supported his hypothesis with evidence of the Moon's internal structure and chemical components, the age of rocks on the Moon, and other geological data. Huang's hypothesis on the origin of the Moon comes from his theory of the genesis of the Solar System. Japanese geologist C. Hayaci said Huang's theory is an innovative school of thought in the field.

There have been four hypotheses on the origin of the Moon so far: First, the Moon was a fragment separated from the Earth; second, the Moon was an independent planet captured by the Earth's gravitational pull; third, both the Moon and the Earth were formed by the same cluster of celestial material; and fourth, the Moon was formed by substances sent out after a huge planetestimal collision with the Earth. Yet all of these theories are considered flawed in certain aspects.