Findings Cast Doubt On Moon Origins

sciencehabit writes "A new analysis of isotopes found in lunar minerals challenges the prevailing view of how Earth's nearest neighbor formed. Geochemists looked at titanium isotopes in 24 separate samples of lunar rock and soil, and found that the moon's proportion was effectively the same as Earth's and different from elsewhere in the solar system. This contradicts the so-called Giant Impact Hypothesis, which posits that Earth collided with a hypothetical, Mars-sized planet called Theia early in its existence, and the resulting smash-up produced a disc of magma orbiting our planet that later coalesced to form the moon."

Comments

This is Real Science

[Spy Handler]

You know how you can tell astronomy is a real science? The people doing it are willing to look at new evidence... even if it casts doubt on their current beliefs.

• They do not insist that the "science is all settled".
• They do not belittle those who come up with hypothesis or evidence that contradicts their current views. (notice that they didn't call this new researcher a "Denier")
• They do not take polls amongst themselves and form a concensus, and then insist they're right on the strength of the fact that they have formed a concensus.

If you see people in a field of "science" doing any of the above, it's not science but something else entirely.

Re:Where is it ? (my keys)

[ShanghaiBill]

We have the technology to find and look very deep or far where isotopes are or where the fartest solar system is. But yet, I can't find my damn keys in my house sometimes.

If technology isn't solving your problem, you aren't using enough: Put an RFID tag on your key chain. While you are at it, you should tag the TV remote too.

Re:Not a contradiction

[Quaoar]

The preferred giant impact model has a Mars-sized impactor with a core-to-mantle ratio equal to the Earth's, with approximately 30% of its mass being in an iron core (http://adsabs.harvard.edu/abs/2004Icar..168..433C). Mars is ~1/6th the Earth's mass. In this impact, the material liberated that eventually forms the moon is iron poor, as the iron core of the impactor sinks into the Earth. That has been the interpretation as to why the Moon's iron core is so small (no more than 3% its total mass), so in this sense the giant impact model produces a satisfactory outcome. Some fraction of the lunar surface is accumulated over the 4 billion years since the Moon formed, but this layer is thought to be very thin, and the meteorites + Apollo samples we use to measure the moon's isotopic ratios come from a range of depths that probe significantly deeper than this surface layer. The fine-tuning argument comes from the fact that for an arbitrary combination of impactor + Earth mass, impact angle, velocity, etc, you'd expect a scatter in the isotope ratios consistent with the typical scatter measured between other bodies in the solar system (say that between Mars and the Earth). Fine-tuning is often employed in intelligent design arguments as they rely on the anthropic principle, but as there's no reason to require the Earth and Moon to have identical isotopic compositions to explain the existence of life, there is no particular reason to favor any particular outcome over the myriad of other outcomes for this particular measurement.

Re:Occam's Razor

[Pope]

Learning is still fun. The trick is to ignore internet comments.