back to article RELICS of the Earth's long lost TWIN planet FOUND ON MOON

Our Moon was born after a young Earth smashed its twin Theia, scientists writing in three studies just published by Nature have suggested. Their intriguing evidence reveals the Moon's origins may have been more incestuous than previously thought. Since the 1980s, scientists studying the Moon have largely agreed on the "giant …

  1. elDog

    So, you're saying that the Earth is also made of green cheese?

    Personally, I like Calvino's words:

    "Didn't I realize it? Or had that been my intention from the very beginning? Before I could think properly, a cry was already bursting from my throat. 'I'll be the one to stay with you for a month!' Or rather, 'On you!' I shouted in my excitement: 'On you for a month!' and at that moment our embrace was broken by our fall to the Moon's surface, where we rolled away from each other among those cold scales."

    - Italo Calvino, Cosmicomics, "The Distance of the Moon"

  2. Mage Silver badge

    Gaia's child

    She calved.

    1. Anonymous Coward

      Re: Gaia's child

      Ah, beef tonight.

      1. dan1980

        Re: Gaia's child


  3. Anonymous Coward
    Anonymous Coward

    Say what?

    > ...a wandering planet, dubbed Theia, came from far, far away...

    Is that really the current theory? Who says? Isn't the common assumption that the two bodies formed in the same zone, making a collision inevitable? When did that change?

    1. Ogi

      Re: Say what?

      Indeed, I've never heard a hypothesis that stated the body that collided with Earth to form the moon was from "far away". In fact the general assumption was that Theia formed very near to earth's orbit, hence the two bodies orbits being able to be perturbed enough to eventually collide.

      I remember many years ago watching a BBC program (Horizon?) that pretty much said this much, including stating that moon rocks collected from the Apollo missions pretty much confirmed this. As such I assumed that "A sister planet collided with Earth to form moon" was the prevailing theory we had for a while now.

      While more evidence is always great in science, I don't think this is as game changing as the article makes it out to be.

      1. Pascal Monett Silver badge

        Game changing ?

        As far as planetary physics are concerned, I think we have passed the point where anything game-changing can occur.

        Like you, I was living under the impression that the sister planet theory was pretty much the most valid theory for a while now. This paper is just another proof that that is the case.

        Good to have, and good to know, but indeed, not anywhere near game-changing.

    2. Kristaps

      Re: Say what?

      It came a long time ago from a galaxy far, far away.

    3. cray74

      Re: Say what?

      Theia's jaunt of X millions of miles is longer than my daily commute or the distance from my chair to the bathroom. I'd call that "far, far away."

  4. Sureo

    Maybe Theia is still there, on the opposite side of earth's orbit, behind the sun where we can't see it.

    1. Anonymous Coward
      Anonymous Coward


      the L3 isn't quite as stable as L4/5, so unless it's very very small (less than a few hundred kilometers in diameter) we would have noticed it due to gravitational effects on our planet.

      1. Anonymous Coward
        Anonymous Coward

        Re: Antichthon

        Kudos for referencing possibly the most bonkers and counter-intuitive idea of the universe ever invented - Philolaus must have found some very funny mushrooms.

        1. graeme leggett Silver badge

          Re: Antichthon

          Or referencing Doppleganger / Journey to the Far Side of The Sun by Gerry and Sylvia Anderson

    2. Anonymous Coward
      Anonymous Coward


    3. Anonymous Coward

      You would still see it - our orbit is elliptical, so it would be visible at certain times of year.

    4. Primus Secundus Tertius


      Even if it had been so placed at one time. perturbations from the other planets would have moved it.

      1. Anonymous Coward
        Anonymous Coward

        Plus recently there are now robotic observation posts that would see it.

        Next: ALCHEMY!

  5. Jim O'Reilly

    Was there even a collision

    Once the wandering planet idea went south, why do we need a collision at all? The moon could just be Earth's twin, created by accretion just like earth was, and captured gravitationally

    1. Anonymous Coward
      Anonymous Coward

      Re: Was there even a collision

      it's certainly possible, though accretion doesn't explain why the moon's iron core is so small relative to earth's, and a glancing impact would.

      1. JCitizen

        Re: Was there even a collision

        Not to mention the fact that we have the only surviving liquid core in the near Sol system. Venus, Mercury, and Mars all have dead cores. Hopefully the Mars rovers will gather something that indicates a theory that could indicate the truth.

        Our surviving internal heat on Earth, suggests to me that a collision happened about 4 billion years ago, or so. I suspect it wasn't so much an impact as a joining of celestial bodies moving in almost the same orbit and speed. This would explain why water is still existent ( besides the Van Allen belt protections - which also rely on a magneto-sphere)

        1. Black Betty

          Re: Was there even a collision

          Beg to differ. Venus is plenty runny beneath the surface. Difference between there and here is, there the entire crust turns over catastrophically every now and then, here we have plate tectonics and relative stability.

    2. Pascal Monett Silver badge

      Not Earth's twin

      If the Moon was Earth's twin formed by accretion, you would expect the Moon to be made of pretty much the same stuff as Earth and in the same ratios.

      That is not the case. The Moon's composition has different proportions of nickel, iron and other significant things, ergo it cannot be our twin.

  6. Graham Marsden

    I reckon...

    ... it was Mondas...

    1. Tigra 07

      Re: I reckon...

      Bastard...beat me by 2 minutes! Have an upvote

    2. Bilby

      Re: I reckon...

      Tell me why; I don't like Mondas.

      (As the Boomtown Rats would no doubt say).

  7. Tigra 07

    Twin planet?

    So that would be Mondas then...

  8. frank ly

    re. "incestuous"

    It sounds more like sibling rivalry.

    1. DropBear

      Re: re. "incestuous"

      Earth and Theia

      sitting in a tree


      (That's how the

      Moon came to be!)

  9. Forget It


    Earth & Moon

    we are talking

    Chalk and Cheese here

  10. ecofeco Silver badge

    Seems a bit of reach

    Not impossible, but it seems any impact is going impart those same chemicals.

  11. Stevie


    The moon was formed as the result of a planet-shattering explosion at the site of the Extremely Large Hyperhadron Collider, a device invented, owned and operated by the Sh'takell M'gafli, a race descended from a common ancestor of Velociraptor some 3 trillion years ago, who venerated mathematics and science to the degree that even the meanest intellect could do complex number manipulation in their heads in a trice (a trick made easier by rote teaching of the -1 times tables in infant's school, a couple of numbers and an arithmetic operator we haven't rediscovered yet and the popular "Lets Do Some Hard Matrix Sums" prime-time holovision show).

    The accident occurred when a drunken caveman wandered into the control room and twiddled a few knobs when no-one was paying attention.

    The resulting explosion pulverised the supercontinent of Zha Gathor, ejecting much of it into space where it coalesced into what we today call "The Moon". Unfortunately the shockwave squished to paste every living being on the planet, melted most of what was left of the planet itself and set fire to the atmosphere, burning it into carbon dioxide, carbon monoxide and particulate soot.

    It was yonks before everything grew back again.

    1. ashdav

      Re: Bah!

      Fundamental flaw in your post "some 3 trillion years ago".

      The universe didn't exist then.

      Looking at your post history (going back to 2008) do you have a life?

      1. Anonymous Coward
        Anonymous Coward

        Re: Bah!

        do you have a life?

        This is coming from some individual who is looking up other people's post history.

      2. Stevie

        Re: Looking at your post history

        My very first comment stalker.

        How spiffy.

  12. Christoph

    So there really was

    An Earth-shattering KABOOM!

    1. Anonymous Custard

      Re: So there really was

      ...and even more things to block the Martian view of Venus.

  13. LaeMing

    Aaaaaand... this mornig I am passing some nutter at the train station complaining that 'America' has found another Earth and is hiding it from us.

    1. PNGuinn

      Re: Aaaaaand...

      What is this mornig of which you speak?

    2. TeeCee Gold badge

      Re: Aaaaaand...

      Probably not a nutter, just an American.

      Paranoia over some "evil government conspiracy" or other seems to come with the passport.

    3. cray74

      Re: Aaaaaand...

      Now we're going to have to spend another $100 million on a big budget sci-fi movie to convince everyone Earth II is just a conspiracy theory...all those geniuses on the internet keep figuring out the US's greatest secrets!

      First it was the Zeta Reticulans at Area 51, then it was the Nazi UFOs, now Earth II...

  14. Allan George Dyer

    Warning: Tautology Alert

    "wandering planet"

    Mine's the one with the geocentric model in the pocket.

  15. PNGuinn

    But shirley the landings were faked?

    But if - as any fule kno - the moon landings were faked the moon rocks would have been brought back from earth.

    From somewhere near Area 51 probably.

    So the chemical constituents would HAVE to be somewhat identical.

    PROOF! PROOF I TELL YOU! The landings WERE faked.

    1. Corp-Rat

      Re: But shirley the landings were faked?

      Of course the moon landings were faked, they were shot in a sound stage on Mars.

  16. Anonymous Coward
    Anonymous Coward

    Universal road rules


    - Now, is it give way to the right, or give way to the left in this system?

    - And, was that an "Orbit-Zone" warning sign?

  17. A Non e-mouse Silver badge

    Front row seat

    Watching that collision play out would be a great spectacle. If only I could get the Doctor to answer his flipping phone and get him to take me to see it.

    1. JCitizen

      Re: Front row seat

      Ach! Ye probably too young a squirt to know how to use a Tardis; and the bloody rotary dialler mechanism!

    2. Pascal Monett Silver badge

      Re: Front row seat

      I propose a scale for such things. Planetary collisions should be 1 Michael Bay.

      Meteors are thus only a milli-Bay.

      A large asteroid could be a centi-Bay.

      1. Alien8n

        Re: Front row seat

        How many Michael Bay's in a George Lucas? (That's no moon!)

    3. Annihilator

      Re: Front row seat

      I'm not sure it would be that spectacular in real-time though?

      1. Anonymous Coward
        Anonymous Coward

        Re: Front row seat

        > I'm not sure it would be that spectacular in real-time though?

        If the impactor was like Mars (6,779 km) and it struck close to Earth's escape velocity (11.2 km/s) then the impactor would travel into the target in 605 seconds, plus some extra for braking. Call it 15 minutes of fun viewing. The big splash would take longer, but perhaps not more than the typical movie run time.

        However, one would need a really dark piece of smoked glass...

        1. Anonymous Coward
          Anonymous Coward

          Re: Front row seat

          Oops, forgot that the Earth before the impact was smaller and had a lower escape velocity, so the show would be a bit longer.

          More popcorn!

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