Why do scientists believe Theia was the size of Mars?

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  • Anonymous
    2 months ago

    Because by offering some kind of reasonably defined answer, it makes them sound more intelligent than when they try to explain what a "singularity" is.

  • Robert
    Lv 6
    2 months ago

    When Theia hit the Earth, it pushed many living dinosaurs deep underground.   Scientists can tell the size of Theia based on the depth of dinosaur fossils at the crater at the Yucatán Peninsula in Mexico.

  • 2 months ago

    Calculations and computer models showed that a collision with a body of at least about 10% of an Earth-mass would be necessary to create enough orbiting debris to form the Moon. 

    In Planetary Science, there were/are often two competing philosophies, known as gradualism versus catastrophism. Catastrophism is generally pooh-poohed as not being real science, since anyone can dream up a rare and unusual event to explain the origin of something. For this reason, the great impactor theory of the origin of the Moon was largely discounted as being "simple catastrophism". Then it was shown Mathematically and statistically that all planets are quite likely to be struck at least once by a body of ~10% of their size during their formation, making the great impactor theory into something highly likely to have happened. (Indeed happening to every planet, not just our Earth.) So the theory was saved, and it remains the most plausible theory as to the origin of our Moon, to this day.

    Cheers. 

  • Bob
    Lv 7
    2 months ago

    Based on the energy of impact estimated to blow enough debris into space to form the moon.

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  • 2 months ago

    It's something of a guess; but, it's based on how massive the Earth is, and what the density of the object must have been to create a short day that the 'new Earth' had once the impact was complete.  A denser object could be quite a bit smaller, while a less dense object would have to be larger; it's thought the mass must have been about 10 to 15% that of Earth today - which is about the mass of Mars. 

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