New study finds 'geologic clock' that helps determine Moon's age

Apr 02, 2014
Mosaic of the near side of the moon as taken by the Clementine star trackers. The images were taken on March 15, 1994. Credit: NASA

An international team of planetary scientists determined that the Moon formed nearly 100 million years after the start of the solar system (4.470 billion years ago), according to a paper to be published April 3 in Nature. This conclusion is based on measurements from the interior of the Earth combined with computer simulations of the protoplanetary disk from which the Earth and other terrestrial planets formed.

The team of researchers from France, Germany and the United States simulated the growth of the (Mercury, Venus, Earth and Mars) from a disk of thousands of planetary building blocks orbiting the Sun. By analyzing the growth history of the Earth-like planets from 259 simulations, the scientists discovered a relationship between the time the Earth was impacted by a Mars-sized object to create the Moon and the amount of material added to the Earth after that impact.

Augmenting the computer with details on the mass of material added to the Earth by accretion after the formation of the Moon revealed a relationship that works much like a clock to date the Moon-forming event. This is the first "geologic clock" in early solar system history that does not rely on measurements and interpretations of the radioactive decay of atomic nuclei to determine age.

"We were excited to find a 'clock' for the formation time of the Moon that didn't rely on radiometric dating methods. This correlation just jumped out of the simulations and held in each set of old simulations we looked at," says lead author of the Nature article Seth Jacobson of the Observatory de la Cote d'Azur in Nice, France.

Published literature provided the estimate for the mass accreted by Earth after the Moon-forming impact. Other scientists previously demonstrated that the abundance in the Earth's mantle of highly siderophile elements, which are atomic elements that prefer to be chemically associated with iron, is directly proportional to the mass accreted by the Earth after the Moon-forming impact.

From these geochemical measurements, the newly established clock dates the Moon to 95 ±32 million years after the beginning of the . This estimate for the Moon-formation agrees with some interpretations of radioactive dating measurements, but not others. Because the new dating method is an independent and direct measurement of the age of the Moon, it helps to guide which radioactive dating are the most useful for this longstanding problem.

"This result is exciting because in the same simulations that can successfully form Mars in only 2 to 5 million years, we can also form the Moon at 100 million years. These vastly different timescales have been very hard to capture in simulations," says author Dr. Kevin Walsh from the Southwest Research Institute (SwRI) Space Science and Engineering Division.

Explore further: A wet Moon

More information: The paper, "Highly siderophile elements in Earth's mantle as a clock for the Moon-forming impact," by Seth Jacobson, Alessandro Morbidelli, Sean Raymond, David O'Brien, Kevin Walsh and David Rubie will be published in the April 3, 2014, issue of Nature: dx.doi.org/10.1038/nature13172

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baudrunner
1.6 / 5 (7) Apr 02, 2014
The cataclysmic collision of the ancient Earth (Tiamat) and a moon of Nibiru, which yielded our moon and which also produced the asteroid belt one hundred million years ago, is the cosmogony described in the Enuma Elish, dictated to Endubsar, master scribe, by the Nibiruan god Enki seven years after the biblical flood and which has come to be interpreted as a confusing metaphorical document which very few people understand. Apparently the "gods" of Nibiru like to name their children after astronomical bodies, not so odd, considering that we name our children after the weekdays and months of the calendar. The "Attestation of Endubsar" describes his encounter with the messengers who delivered him to Enki for his services. They descended before him in an aircraft that landed on four legs which emerged from its belly. The "Attestation of Endubsar" is an affidavit relating this event which Enki asked him to produce.
Dr_toad
Apr 02, 2014
This comment has been removed by a moderator.
Nik_2213
5 / 5 (2) Apr 02, 2014
Certainly reasoning from an erroneous premise or three...

How will 'Noachian' believers handle that recent tablet find with the Gilgamesh version that describes the building of a circular reed raft with a hut, all in a week ? And a nasty, but 'local', river flood ??
Torbjorn_Larsson_OM
5 / 5 (4) Apr 02, 2014
It is an ingenious method, and the proposed Earth age of ~ 4.47 Ga is consistent with the oldest 4.4 Ga old zircon suggesting a cool Earth. A crust can form in 10-100 Ma.

@Dr_toad: A nutcase with a serious case of "I didn't even read the article" (re the dating) and "I don't even care for the science" (re known myths, re the observed absence of a global flood, re the use of magic ideas).

GSwift7
5 / 5 (4) Apr 03, 2014
the cosmogony described in the Enuma Elish, dictated to Endubsar, master scribe, by the Nibiruan god Enki seven years after the biblical flood

Nutcase.


I believe the following excerpt is related to that topic, and might help explain the basis of the Niributian theory:

Picture yourself in a boat on a river,
With tangerine trees and marmalade skies.
Somebody calls you, you answer quite slowly;
A girl with kaleidoscope eyes


Some people will get this and laugh, and others will need an explanation.
Bapi
not rated yet Apr 04, 2014
GIANT IMPACTTHEORY of origin of Moon inmid-1970s,emerged.William K. Hartmann & D.R. Davis (Planetary Sciences InstituteTucson AZ) hypothesized that Earth, in course of its accumulation,underwent some majorcollisions with other bodies had substantial fraction of its mass and that these collision produced large vaporclouds that they believe might play a role in the formation of the Moon.A collision with a body having at least the mass of Mars would be needed to give the Earth the present angular momentum of the Earth-Moon system, In1984, scientific conference on origin of Moon was organized in, Hawaii, number of papers were discussed on various aspects of the giant impact theory.The giant impact theory emerged "fashionable" theory, but everyone agreed that it was relatively untested and that it would be appropriate to reserve judgement on it until a lot of testing has been conducted. The next step clearly called for numerical simulations on supercomputers.The Moon is computationally
Bapi
not rated yet Apr 04, 2014
Continued......The Moon is computationally unique,having not more than 4% its mass in form of iron core.This contrasts with Earth, a typical terrestrial planet's bulk composition, which has about one-third of its mass in form of iron core. Thus, simulation could notbe regarded "successful" unless material left in orbit was iron free or nearly so and was substantially in excess of mass of Moon. This uniqueness highly constrains 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
Professor Pranab kumar Bhattacharya, Miss Upasana Bhattacharya, Rupak Bhattacharya, Ritwik Bhattacharya, Rupsa Bhattacharya Dalia Mukherjee Debasis Mukherjee

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