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Long ago, when the dinosaurs roamed the world, something happened....

In this alternate universe, something happens that shifts the axis of the Earth from its original position during the Mesozoic Era to a final position with the North Pole situated near Zhezgazgan, Kazajstan and the South Pole around 47ºS 113ºW.

And, of course... dead dinosaurs.

  • I would prefer tectonic plates to survive, although more fault lines isn't a problem.

  • I'm looking for "Natural and plausible" causes. In the end, Earth is still habitable and in orbit of the Sun.

Question: What could cause this to happen?

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    $\begingroup$ An asteroid with the power to change the axial tilt of the Earth would not be an asteroid, it would be a smaller planet. There would be no visible crater because the entire world would turn into molten lava. Dinosaurs would die out, along with every other living organism, and evolution would have to start from scratch. Is that the effect that you are looking for? $\endgroup$
    – KeizerHarm
    Jan 24 at 13:01
  • $\begingroup$ Sure, that works. Would the tectonic plates suffer a big change or would they melt too? I'm assuming that there won't be any crater to be seen. $\endgroup$ Jan 24 at 13:03
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    $\begingroup$ There would be no tectonic plates, because there would be no crust. The entire planet would be magma again for who knows how many millions of years. Chances are we would get a second moon, or lose the current one. $\endgroup$
    – KeizerHarm
    Jan 24 at 13:06
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    $\begingroup$ Changing the axial tilt without melting the planet would have to be not one huge impact, but countless small ones over a very long period of time. $\endgroup$
    – KeizerHarm
    Jan 24 at 13:24
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    $\begingroup$ Would you mind if I change the question FROM "Alternate Earth gets impacted by an asteroid that changes the position of the rotation axis, what are the characteristics of the impact?" TO "Alternate Earth, the position of the rotation axis gets changed, what happened?"? $\endgroup$ Jan 24 at 13:39

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You're in luck

The Alvarez Hypothesis, which is the source of our common belief that an asteroid killed the dinosaurs, has a report from some of its supporters that claim the Earth's axis did, in fact, shift due to the impact.

in a 1953 publication, geologists Allan O. Kelly and Frank Dachille analyzed global geological evidence suggesting that one or more giant asteroids impacted the Earth, causing an angular shift in its axis, global floods, firestorms, atmospheric occlusion, and the extinction of the dinosaurs. (Source)

Further, there are articles that describe how the Earth's axis can shift due to impacts (for example...).

The question is, are you looking for "realistic" or "suspension of disbelief"?

I'm not a fan of "realistic." I think too many writers get bogged down in the details of "realism." It beats me why. There may only be two people who ever read their work who might know they were not completely "realistic" — and if the story's good, they won't care.

So, suspension-of-disbelief says you can use an asteroid impact to shift the axis. Note that a direct impact will shift the axis very little. An oblique impact will shift it more (and possibly knock a new moon into orbit). Where the asteroid impacts, and at what angle, have a lot to do with how much the Earth could believably be rolled over.

Further, you could use a series of impacts, say days or weeks apart, that achieve the axial shift and kill the dinosaurs without the trouble of turning the Earth's surface into soup.

But you have other alternatives

Another alternative is one or more earthquakes. While our current evidence suggests they won't move the axis a lot, what do you care? Think of earthquakes in terms of slamming down your garage door. Slam that tectonic plate against the others hard enough, and you shift the axis, screw up the weather, and kill a whole lot of dinosaurs.

Yet another is volcanism. Not any ordinary volcano will do. You'd need something like the entire Yellowstone Caldera going up like Mt St. Helens. This solution might be the most believable for keeping the tectonic plates intact.

If you want something more exotic, let's have a micro black-hole wander through the system

Of course, an external gravity source could believably shift the Earth's axis. Let's have a small black hole wander through the solar system. It passes Earth at just the right place to jerk the planet around, shifting the axis. The consequences would definitely kill dinosaurs!

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  • $\begingroup$ I think I like the Massive eruption plus Great Earthquake. I might be able to sell it as the origin of Noah's flood. $\endgroup$ Jan 24 at 22:30
  • $\begingroup$ You could have a large planetary body get crushed somehow, maybe passing too near Jupiter, becoming a string of large asteroids all on the same trajectory... $\endgroup$
    – LSerni
    Jan 24 at 23:28
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Not really, but -- remove the Moon.

There is a theory (whose timeframe isn't really useful to us, rather the opposite) that the Earth's axis of rotation can be driven into chaotic regime, somewhat like the Dzhanibekov effect, by the absence of a large Moon.

So, you can imagine that the Moon is actually less stable than it looks, and in the Mesozoic a catastrophic impact succeeded in fragmenting it in a non-cataclysmic way - nothing like Moonfall, rather something à la Ceres Solution. The Earth became a ringed planet like Saturn, and the rings slowly decayed - and, meanwhile, under the resonant pull of the other planets, the axis began to wander. Way faster than the theory allows, but that's a detail.

This also means that nowadays' continents would look nothing like today: without a Moon, the continental drift would probably have evolved differently (and more slowly).

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    $\begingroup$ Ooooh, this is a fun idea. Hit the moon with a big enough object and not only could you model it as a sudden change of gravity, but you could theorize that a lot of the mass would be pushed out of Earth's orbit. And it would look good in a movie. $\endgroup$ Jan 24 at 23:17
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I would prefer to keep the tectonic plates solid. Non necesarily intact.

I think that is not possible.

As per XKCD What Of no. 26, it would take a dino killing asteroid every couple days just to reduce Earth's angular momentum by 0.00000925925%. You wish to rotate the axis by almost 45%, so the amount of energy is such that you either need a major planetary impact (which melts the crust) or a steady stream of comets/asteroids coming in for longer than the solar system will exist. Also notice that the Sun and the Moon tend to pull Earth's axial tilt closer to 0⁰ over billions of years, which makes what you want even harder.

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  • $\begingroup$ Q: I wonder where these 12 decimals precision originate from.. you assumed impact velocity and impact angle to be exactly equal to the Yucatan impact that - allegedly - killed the dinosaurs ? According to Scientific American the angle was between 30 and 60 degrees.. blogs.scientificamerican.com/life-unbounded/the-angle-of-doom resulting in a 50km wide and 30km deep crater. $\endgroup$
    – Goodies
    Jan 24 at 16:59
  • $\begingroup$ @goodies Randall Munroe assumes a perfect 0⁰ impact everytime in order to optimize the transfer of momentum. That's just to drop the day length by 0.8 seconds. $\endgroup$ Jan 24 at 18:11
  • $\begingroup$ Is this an answer to the question, a Frame Challenge, or an extended comment? $\endgroup$ Jan 24 at 20:51
  • $\begingroup$ @JoinJBHonCodidact Frame challenge answer. $\endgroup$ Jan 24 at 21:00
  • $\begingroup$ Thanks. IMO it's always good to mention that in the answer. My knee-jerk reaction was to think it was an extended comment. $\endgroup$ Jan 24 at 21:08

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