Earth Tipped on Its Side During the Age of Dinosaurs–and Not Just Once | Hacker News Reader

Earth Tipped on Its Side During the Age of Dinosaurs–and Not Just Once

gizmodo.com

3 pointsgumby10 comments

Open articleView on HN

The earth wobbles. It doesn’t “tip”.

The title is misleading. The article is about the magnetic poles moving and the implications.

> The article is about the magnetic poles moving and the implications.

That's incorrect, see the wikipedia article:

https://en.wikipedia.org/wiki/True_polar_wander

It's about the physical axis of rotation moving around.

It'd be nice to access the paper at science.org...

The headline makes it seem like the Earth actually flips over (which is impossible for a spinning ball of liquid as far as I can reason about it). The article is about the magnetic poles.

> so it appears as if the Earth tips over on its side. And this phenomenon may have had a greater impact on our planet’s environment than scientists thought.

I'm no climate scientists, but I'd think "tipping over the earth on its side" would mess up the weather more than just a bit. The title and the intro suggests that the planet will flip "90 degrees", the rest of the article does nothing to explain this intro.

Exactly. I once had the theory that crocodiles in the Arctic and glaciers in the Sahara were just the effect of the axis tumbling, but then Claude confidently educated me that, thanks to some explicit calculations by Einstein(!), it's not possible for a spinning ball to tumble that much.

No I think the orientation of the earth changed relative to its axis. Earth is constantly changing and its density is not evenly distributed, so you see changes in its orientation with its axis. If we suddenly moved (just imagine) 10% of Earth's mass to a band forming a great circle from N45°E0° directly to its antipode at S45°E180°, Earth's axis would shift to make this its new equator.

This wiki page could be worded a little more clearly though, it sounds like the axis could have shifted by ~25°? Or Asia could have migrated due to the shift of the axis ~174 million years ago? 25° change in axis would be quite dramatic.

https://en.wikipedia.org/wiki/True_polar_wander

What do you mean when you say “orientation relative to its axis”?

The Earth is essentially a spinning ball of liquid that flows around and with a crust floating on top that we can walk around on. Pretty much the only ‘orientation’ it can have is the axis that it spins around.

Most of the comments are saying that this is only about the magnetic pole wandering.

However, it also says

'the “entire solid Earth reorients to restore this alignment,” according to the paper. But the core and climate belts remain fixed,'

So this is indeed about physical Earth tipping, and it seems that it's trying to say that it happens during times of "polar wander".

Regardless of what it is saying it is so badly written it has no place in public discourse.

Yeah, the earth does both. Magnetic wander is observable on human timescales, but spin wander (true polar wander) is not. We believe we've seen it in other bodies in the solar system too.

Reply on news.ycombinator.com