Реферат: Theories Of The Origin Of The Moon

?The Moon is a compositionally unique body, having not more than 4% of its

mass in the form of an iron core (more likely only 2% of its mass in this

form).

This contrasts with the Earth, a typical terrestrial planet in bulk

composition,

which has about one-third of its mass in the form of the iron core. Thus, a

simulation could not be regarded as ?successful? unless the material left

in orbit

was iron free or nearly so and was substantially in excess of the mass of

the

Moon. This uniqueness highly constrains the conditions that must be imposed

on

the planetary collision scenario. If the Moon had a composition typical of

other

terrestrial planets, it would be far more difficult to determine the

conditions that

led to its formation.

The early part of this work was done using Los Alamos Cray X-MP computers.

This work established that the giant impact theory was indeed promising and

that

a collision of slightly more than a Mars mass with the Earth, with the

Earth-Moon

angular momentum in the collision, would put almost 2 Moon masses of rock

into

orbit, forming a disk of material that is a necessary precursor to the

formation of

the Moon from much of this rock. Further development of the hydrodynamics

code made it possible to do the calculations on fast small computers that

are