If a ‘Big Whack’ Made the Moon, Did it Also Knock the Earth on Its Side?

Nov 6, 2016

By Kenneth Chang

A cataclysmic collision not only created Earth’s moon, but may have also knocked Earth over on its side, scientists proposed.

In a paper published last week by the journal Nature, the scientists say their numerical simulations indicate that the collision of a Mars-size object with the early Earth left our planet tilted at an angle of 60 to 80 degrees and spinning rapidly, once every two and a half hours, or almost 10 times as fast as today.

But the simulations also show how the dynamics of the moon and Earth slowed down and straightened up over the next four billion years of the solar system, leaving them where they are today.


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2 comments on “If a ‘Big Whack’ Made the Moon, Did it Also Knock the Earth on Its Side?

  • @OP – In a paper published last week by the journal Nature, the scientists say their numerical simulations indicate that the collision of a Mars-size object with the early Earth left our planet tilted at an angle of 60 to 80 degrees and spinning rapidly, once every two and a half hours, or almost 10 times as fast as today.

    That sort of impact energy would have to go somewhere to directional create spin or an elliptical orbit, so if that’s what the calculations show, it seems likely.

    But the simulations also show how the dynamics of the moon and Earth slowed down and straightened up over the next four billion years of the solar system, leaving them where they are today.

    It also seems likely that tidal drag would have slowed the spin, raised the Moon’s orbit (as it is still doing), and that interactions with the Sun and other planets, would have worked to circularise the Earth’s orbit.



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