The Moon – Its Age and Origin – an Important Question Still Under Discussion

The Moon – Its Age and Origin – an Important Question Still Under Discussion

Author: Stig Kristoffersen

The moon – its age and origin – An important question still under discussion

Age of the moon

Prof. Oliver Schaeffer and Postdoctoral Fellow John Funkhouser were part of the team that announced the first dating of the age of the Moon to be about 4 billion years. This was based on the rock samples brought back by the Apollo 11 astronauts, the first humans to walk on the Moon, in July, 1969. These findings, the first scientific report based on analysis of lunar material actually retrieved from the Moon, were reported in the September 19, 1969, issue of Science under the authorship of "The Lunar Sample Preliminary Examination Team," of which Prof. Schaeffer was a member. They were presented in a much more extensive form at a Lunar Science Conference of all mission investigators in Houston and published in an extraordinary 380-page "Moon Issue" of Science on January 30, 1970.

Stony Brook's team, led by Oliver Schaeffer, determined the concentration and isotopic signature of argon gas contained in lunar samples. They combined these data with potassium concentrations for the same samples to derive an age of about 4 billion years for the Moon. This initial determination by the Stony Brook-led team has been corroborated by several other research teams using complementary techniques. Obtaining the age of the moon, our nearest neighbor, is a scientific milestone that has deepened our understanding of the early history of Earth and helped set boundaries for dating the origin of life on Earth.

How was the Moon formed and how did it come to have its present orbit around the Earth?

There are five dominant theories which have been proposed for the formation of the Moon.

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.

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 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.

Preferred theory of origin for the moon

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 still a matter for discussions in the scientific environment and there are many details remaining to the accounted for.

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About the Author:
He has a background as civil engineer and geoscientist. He has worked mainly within the oil and gas industry from the mid 1980s. He has written some few fictional novels as well as author of some professional litterature within oil and gas sector, he is now an editor of some web sites, mainly within the travel business.