Overlooked No More: Inge Lehmann, Who Discovered the Earth's Inner Core

Posted by Hooke 12/22/2025

Overlooked No More: Inge Lehmann, Who Discovered the Earth's Inner Core(www.nytimes.com)

92 points | 21 comments

kasperni 12/26/2025|

She is not a household name in Denmark. But we do have a big mural of her, here in Copenhagen [1].

[1] https://files.mastodon.social/media_attachments/files/112/99...

nosianu 12/26/2025||

I had to look twice, and then check Wikipedia, when I saw "1888-1993" there.

* 13. Mai 1888 in Kopenhagen

† 21. Februar 1993 in Kopenhagen

That's 104 years, 9 months, and 8 days!

slu 12/26/2025||

Google Street View link showing the murial: https://maps.app.goo.gl/nfSzrb3CFPKowZ4p9?g_st=ac

perigrin 12/26/2025||

All of modern geology stands upon her work.

wasting_time 12/26/2025||

https://archive.is/jTCRB

tekla 12/26/2025||

She was hardly overlooked, she won many honours for her work during her time.

> This article is part of Overlooked, a series of obituaries about remarkable people whose deaths, beginning in 1851, went unreported in The Times.

hopelite 12/26/2025|

[flagged]

pfdietz 12/26/2025|

> It explained how the Earth generates the magnetic field that protects the planet from cosmic radiation,

Our protection from cosmic radiation is mostly due to Earth's thick atmosphere, not its magnetic field.

andsoitis 12/26/2025||

> Our protection from cosmic radiation is mostly due to Earth's thick atmosphere, not its magnetic field

Primary defense against cosmic radiation: magnetic field

Secondary defense: atmosphere

https://science.nasa.gov/science-research/earth-science/eart...

pfdietz 12/27/2025||

Yeah, that's nonsense. The radiation in low Earth orbit is only a bit less than above the magnetosphere, and most of that difference is from shadowing by the Earth itself. In contrast, there's a massive decrease in radiation from LEO to to sea level.

Radiation at ISS: 144 mSv per year

Radiation on a trip to Mars: ~340 mSv per year

Cosmic radiation at sea level: about 0.4 mSv per year

The atmosphere is doing the heavy lifting in shielding us from cosmic radiation, not the magnetosphere.

magicalhippo 12/27/2025|||

> Radiation at ISS: 144 mSv per year

> Radiation on a trip to Mars: ~340 mSv per year

This seems to track with research that during a geomagnetic excursion[1], where the field strength dropped to about 10%, the cosmic radiation seems to have roughly doubled[2].

[1]: https://en.wikipedia.org/wiki/Geomagnetic_excursion

[2]: https://www.eurekalert.org/news-releases/1041098

pfdietz 12/27/2025||

To steelman the argument, perhaps what the magnetosphere is doing is stopping the atmosphere from making too much carbon-14. In shielding the surface from energetic cosmic rays, neutrons are produced, and these transmute N-14 to C-14 by the (n,p) reaction.

andsoitis 12/27/2025|||

> Yeah, that's nonsense.

Assuming you're right, why do you suppose so many publications get it wrong?

Not only the NASA one I linked to but also Wikipedia for example: https://en.wikipedia.org/wiki/Cosmic_ray

Or the European Space Agency: https://www.esa.int/Science_Exploration/Space_Science/Cluste...

You will forgive me if I take their assessment more seriously than yours, but I'm open to correcting my understanding.

pfdietz 12/27/2025||

It's in the interest of NASA (and the ESA) to hype the importance of the magnetosphere. After all, they are given money to investigate it, so the more important it is perceived, the more money they can expect to get.

andsoitis 12/28/2025||

> It's in the interest of NASA (and the ESA) to hype the importance of the magnetosphere. After all, they are given money to investigate it

I don’t know that that is a good reason to cause you to you think they’re lying.

NASA also extensively investigates Earth's atmosphere.

They use missions like Aura, CALIPSO, and upcoming ones like AOS and INCUS to monitor ozone, clouds, aerosols, and storms, providing crucial data for forecasts and climate science.

pfdietz 1/5/2026||

They aren't "lying", they're "stretching the truth".

I don't know why you'd expect a self-interested organization to do anything else.

nephihaha 12/26/2025|||

The magnetic field deflects particles from the Solar Wind, whereas the atmosphere blocks a lot of the radiation as I understand it.

pfdietz 12/26/2025||

The solar wind != cosmic radiation.

Qem 12/26/2025|||

Without magnetic fields, the solar wind strips away atmospheres, like what happened to Mars.

pfdietz 12/26/2025||

This is questionable.

https://earthscience.stackexchange.com/questions/14915/does-...

Qem 12/26/2025||

Thank you. I thought that was settled matter.

nobodyandproud 12/26/2025|||

I don’t see any problems with the quote.