> The scientists say their model of inner core movement also explains the variation in the length of day, which has been shown to oscillate persistently for the past several decades.
How do we measure persistent changes to the length of a day on Earth? This seems like a maddeningly slippery problem.
- Geosynchronous sattelites? What if they're slightly off?
- Star readings? Can we measure that precisely enough from the surface to find tiny fractions of change?
- Any surface-based reading also has to deal with the non-spherical nahure of Earth, and its wobble (the motion that gives us seasons)
How do they do it?
It's fascinating to think there's so little we really know of our own planet. Our knowledge about the inner workings of Earth's core are all from indirect measurements, and there's a fundamental limit to the resolution of our models using these methods. I'm sure there's so much more to learn, and many more surprises, if we discover novel new ways to inspect deep underground.
This article seems like it's trying to imply that the core changes position relative to the earth, when all the actual details, and the linked journal article [0] only talk about changes in rotation speed relative to the surface. This appears to be a uniquely and bafflingly bad case of science journalism.
Anyway, it would be cool if this led us to understand where mantle plumes come from. I don't know how likey that is, but it seems that the dynamics between the core and mantle is the right place to look.
[0] https://www.science.org/doi/10.1126/sciadv.abm9916 <-- Just read the abstract of this instead
Since the change in length-of-day is mentioned, is seems more accurate to say that both the inner core and the crust oscillate with respect to each other.
OT - but the insistence on italicized type for this article is rather bizarre. No other USC article I've ever seen follows this formatting.
Nikola Tesla is not surprised.
interesting. does anyone knows if this affect gravitational forces somehow?
I knew I felt something.
Wait... is it then actually possible it's not the whole Earth, as suspected by Dzhanibekov at one point, but just the inner core that might flip axis due to having an intermediate axis of inertia if the metals/density are not evenly distributed?