Scientists solve long-standing mystery surrounding the moon's 'lopsided' geology

https://phys.org/news/2024-04-scientists-mystery-moon-lopsided-geology.html

by wglb • 2 years ago

63 17 2 years ago

somat• 2 years ago

Speaking of anomalous geology, I went down a bit of a rabbit hole this evening, I was reading about survey grade compasses, and they are balanced to account for magnetic dip, the closer you get to the poles the more dip you have. And the manufacturer helpfully provided a map to help you pick the best dip correction. Looking at the credited source(the world magnetic model) for a bit greater resolution... And, what the heck is that in the south Atlantic ocean.

https://www.ncei.noaa.gov/sites/default/files/2022-02/Miller...

I think it is this, There is a large(very large) density structure in the mantle in that general area and it appears to drive weak van allen fields in the south atlantic.

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

grugagag• 2 years ago

I’ve heard of it but wasn’t aware it’s that ‘anomalous’. It looks like it would make a compass in the area very hard to use

throwway120385• 2 years ago

Only if you're traveling fast relative to walking speed. You can still generally navigate by direction in the area, and it looks like it covers such a large area that in EG a 5 mile by 5 mile area you could still reliably set your declination and navigate with minimal error. The field lines seem to change direction in an arc the size of South Africa, for example. But it just means that if you're westerly or easterly in South Africa you need to be very cautious to set the declination on your compass and not assume it varies little, like you can in the Pacific Northwest.

MPSimmons• 2 years ago

Spacecraft going through the SAA experience dramatically higher radiation hits.

hydrogen7800• 2 years ago

I was reading about survey grade compasses, and they are balanced to account for magnetic dip, the closer you get to the poles the more dip you have.

Wet, or whiskey compasses used in aircraft are counterweighted to account for this. There are mnemonics for pilots to know how to handle the error induced by this counterweight: "OSUN—overshoot south, undershoot north" and "ANDS—accelerate north, decelerate south".

https://www.aopa.org/news-and-media/all-news/2012/may/flight...

psunavy03• 2 years ago

And generally if you're using the whiskey compass, something is wrong, because most aircraft besides the most basic of VFR bugsmashers have other devices as a primary heading reference, be it a simple gyrocompass on a Cessna 172 or a full GPS-enabled strapdown inertial navigation system on a jet aircraft.

westurner2• 2 years ago

Existing gravimeter tech:

"City-size seamount triple the height of world's tallest building discovered via gravitational anomalies" (2024) https://www.livescience.com/planet-earth/rivers-oceans/city-...

"Kerr-enhanced optical spring for next-generation gravitational wave detectors" (2024) , and/or Tantalum; https://news.ycombinator.com/item?id=39957123

uolmir• 2 years ago

Great article. As someone with a geology background working in an Earth and space science department, I've greatly appreciated everything I've learned from the planetary scientists and meteorite researchers. There's just so much that we now understand about how our solar system formed and arrived at its current state. The explosion of exoplanet research on top of that and how those two fields inform each other has also been exciting to follow.

karol• 2 years ago

Fortuitously, the lump of the molten rock positioned itself on a orbit of the Earth just so that it size covers the Sun perfectly. We all believe that!

pinkmuffinere• 2 years ago

I detect sarcasm — are you saying the existence of solar eclipses are evidence for the existence of God?

Aside from being a beautiful curiosity, solar eclipses aren’t very impactful for humanity (correct me if I’m wrong here), so I don’t see why they would indicate a creator.

practicemaths• 2 years ago

I'm going to assume when you say not very impactful to humanity that you mean in a physical sense that it doesn't significantly change our environment directly because of it.

Certainly has had an impact on humanity in a cultural sense.

hnfong• 2 years ago

That aside, I think it can be a serious scientific question as well.

i.e. Is there a scientific explanation for the fact that the ratio between the diameter of the Sun and Moon are the same as the ratio between their distances to Earth such that they look almost exactly the same size to us?

We can of course say it's coincidence -- and that may be the case, but if we use "coincidence" to explain away anything we can't readily explain (instead of trying to find answers), there'd there'd be no scientific progress at all.

Ideally, the model of how the Moon formed _should_ give an explanation to that. If that turns out to require (for example) the existence of ancient space aliens fine tuning parameters in our solar system, well, IMHO people can decide for themselves whether they think this is more likely, or the fact that the ratios of the celestial objects fit just perfectly.

------

Btw, slight nit with your logic -- if solar eclipses are impactful for humanity's survival, one can invoke the anthropic principle to explain why it's a necessity in an environment that gave rise to humans. But it seems they're not impactful, so in that way, it seems that the possibility of a creator is relatively increased.

eichin• 2 years ago

No we don't? It was closer and thus over-covered it (and is spiraling out - solar eclipses will no longer happen in 600 million years or so.)

cryptonector• 2 years ago

It still over-covers it sometimes. Eventually it never will.

westurner2• 2 years ago

How does this finding compare with those from this simulated video of the moon forming?

"Collision May Have Formed the Moon in Mere Hours, Simulations Reveal" https://www.nasa.gov/solar-system/collision-may-have-formed-... https://youtu.be/kRlhlCWplqk

And this, from the moon:

"Scientists discover huge, heat-emitting blob on the far side of the moon" (2023) https://www.livescience.com/space/the-moon/scientists-discov...

"Remote detection of a lunar granitic batholith at Compton–Belkovich" [from a dormant volcano] (2023) https://www.nature.com/articles/s41586-023-06183-5

Scientists solve long-standing mystery surrounding the moon's 'lopsided' geology

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