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Time to rethink the Moon’s formation

moon pic.jpgPosted on behalf of Lee Sweetlove

Either the Moon is significantly younger than thought, or scientists need to completely rethink how it formed. That’s the conclusion of new isotope dating of the lunar crust published in Nature today.

The Moon was created when a Mars-sized body hurtled into the newly-formed Earth. Debris from the collision ended up in orbit around the Earth, and eventually accreted to become the Moon. It is thought that the satellite was initially a molten ball of rock – a global magma ocean – that gradually cooled at its surface to form a solid crust.

A study by geochemist Lars Borg at the Lawrence Livermore National Laboratory in California and his colleagues now suggests that this process took tens of millions of years longer than thought. Using improved isotope dating techniques, they have revised the age of a class of lunar crustal rocks known as ferroan anorthosite (FAN). According to their measurements of a sample of FAN collected during the Apollo 16 mission in 1972, the Moon’s crust solidified 4,360 million years ago, around 200 million years after the formation of the Solar System.

Previous estimates of the age of FANs are highly variable, covering a 200-million-year range, but Borg’s result is 60 million years younger than the previous reliable youngest estimate.

Borg describes this as an “extraordinarily young age” and says that on face value it means that the Moon formed surprisingly recently. Alternatively, scientists would need to rethink the process of lunar formation, to explain how the FAN rock could have solidified later on.

Borg’s discovery comes hot on the heels of a proposal that the Earth once had two moons, both created in the same giant impact, that later merged in a slow-motion collision (see “Early earth may have had two moons“).

If so, then one would expect two temporally distinct FANs on the moon: an older class derived from the smaller companion moon, and a younger class from the main body of the moon, which would have cooled more slowly. This could explain the varying ages that have been reported for lunar FAN samples, but Borg is cautious: “The ages of most FANs are not determined with enough confidence or with enough temporal resolution to rigorously assess this possibility.”

Image courtesy of RONg, via Flickr under Creative Commons.


  1. Report this comment

    David Kostoski said:

    I think that extraterrestrial intelligent nature is everywhere around us in fact they placed the moon to make the environment on earth as it is and also they gave humans intelligence since why any other creature does not posses it ALIENS FUCK YEAH!

  2. Report this comment

    John King said:

    You want to know the true age of the Moon? Find the oldest rock on the South Pole. Simple..

    Antarctica is the remnant of a planet that struck the Earth. When this happened, it caused the great flood. A chunk of the planet skimmed the Earth up to India and formed the Moon. Australia had most of it’s surface stripped away due to the initial blast and wall of water that swept across the entire planet.

    Take a good look at what I’m talking about. Google Earth…

  3. Report this comment

    David Battle said:

    The tone of this article seems a bit sensationalistic given that we’re talking about a difference in age estimates of a at most a few percent. Terms like “recently” shouldn’t apply to things that are “only 4.3 billion years old” when we previously thought they were 4.4 billion years old.

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    Netsivi said:

    The info is that “the Moon’s crust solidified 4,360 million years ago,”

    that is not later than 4,360 million years ago. The Moon could be formed much earlier without contradicting Borg’s study, even if Borg’s study is sufficiently accurate. Also, future research based on another compound might point out earlier dates.

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    James T. Dwyer said:

    Firstly, to be clear, the new estimate is the date that the moon’s surface rock crystalized, not when the moon was created.

    As I understand, the issue is with estimations of the amount of time necessary for a moon sized mass to cool.

    I suspect that the estimations of lunar cooling duration did not adequately consider the proximity of the Earth to the early moon, its direct radiative heating and the effects of Earth’s tidal forces imparted to the moon. Perhaps these factors could have slowed the moon’s cooling and eventual crustal crystalization.

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    syl said:

    I’m a bit late in reading the article and i could be way off base so bare with me: If the collusion event resulting in the moons creation is valid then its reasonable to think that some of the ‘earths debris’ (along with that of the Theias) was thrown far enough to have escaped the earths ‘re-accretion’ process. Its not much of a stretch to reason the possibility of some of the moons future impacts being the result of this wandering planetary debris. The moon is obviously no stranger to uninvited guests and it wouldn’t surprise me to hear of its true surface being buried under layers of impact leftovers.

    The question is: how can they be sure they were dating an actual piece of the moon and not the remnants of a long past impact events.

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    Tadeusz Tumalski said:

    In the ‘NATURE | VOL 412 | 16 AUGUST 2001’ Robin M. Canup and Erik Asphaug wrote:

    “The Moon is generally believed to have formed from debris ejected
    by a large off-centre collision with the early Earth…”

    But believing is no mater of a physical science, this is the mater of a religion. So in the last decades the “Giant Impact”-hypothesis became a kind of religion, which is celebrated by hundreds of physicists and journalists. Thanks the strong believing in the “impact ideas” became each scientist and journalist a member of a sect, and celebrate a kind of ritual mass to the simple question: “are the impacts generally possible, and what about Mercury?”

    The last Big Splash
    idea of Eric Asphaug and Martin Jutzi is a proof of a high level of desperation in the question about our Moon.
    The conclusion is very simple: the ‘single’ (Giant) or ‘multiple impact ideas’ that is the false way! We waste the time and taxpayer’s money, we need a new begin in this question.

    The new way begins in the article: Earth-Moon system; The origin

    The moon must have hollow spaces inside, otherwise is the density paradox of the moon not solvable.
    Seismograms of moon-quakes lasting up to 100 min, clearly demonstrate the existence of hollow spaces inside the moon which is a further proof for the thesis that our moon is a kind of cosmic pumpkin.

    Best regards
    Tadeusz Tumalski

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