Theories of Formation for the Moon

25 March 2012, 10:47.

An extremely important question is that of how the Moon was formed and came to have its present orbit around the Earth.

Five Serious Theories

Five serious theories have been proposed for the formation of the Moon (not counting the one involving green cheese):
1: The Fission Theory: The Moon was once part of the Earth and somehow separated from the Earth early in the history of the Solar System. The present Pacific Ocean basin is the most popular site for the part of the Earth from which the Moon came.

2: The Capture Theory: The Moon was formed somewhere else, and was later captured by the gravitational field of the Earth.

3: The Condensation Theory: The Moon and the Earth condensed together from the original nebula that formed the Solar System.

4: The Colliding Planetesimals Theory: The interaction of earth-orbiting and Sun-orbiting planetesimals (very large chunks of rocks like asteroids) early in the history of the Solar System led to their breakup. The Moon condensed from this debris.

5: The Ejected Ring Theory: A planetesimal the size of Mars struck the earth, ejecting large volumes of matter. A disk of orbiting material was formed, and this matter eventually condensed to form the Moon in orbit around the Earth.
Constraints from Recent Data

A detailed comparison of the properties of Lunar and Earth rock samples has placed very strong constraints on the possible validity of these hypotheses. For example, if the Moon came from material that once made up the Earth, then Lunar and Terrestrial rocks should be much more similar in composition than if the Moon was formed somewhere else and only later was captured by the Earth.
These analyses indicate that the abundances of elements in Lunar and Terrestrial material are sufficiently different to make it unlikely that the Moon formed directly from the Earth. Generally, work over the last 10 years has essentially ruled out the first two explanations and made the third one rather unlikely. At present the fifth hypothesis, that the Moon was formed from a ring of matter ejected by collision of a large object with the Earth, is the favored hypothesis; however, the question is not completely settled and many details remain to the accounted for.


Leave a Reply

Random Articles

baltic Sea UFO Last summer, while on a treasure hunt between Sweden and Finland, the pair and their research associates made headlines worldwide with the discovery of a 200-foot wide unidentified object at the bottom of the Baltic Sea. Now a .

Artist’s impression of planets around a star Newly discovered planet could hold water 18 March 2010 The Corot satellite strikes again with another fascinating planet discovery. This time, the newly discovered gas giant planet may have an interior that closely resembles those .

Space station flight engineer Andre Kuipers will be in a unique position to observe Earth Hour, a public awareness project that asks people to turn off their lights for one hour at an appointed day and time.


Should we invest in the space elevator?

View Results

Loading ... Loading ...

Follow us: