Welcome to DU! The truly grassroots left-of-center political community where regular people, not algorithms, drive the discussions and set the standards. Join the community: Create a free account Support DU (and get rid of ads!): Become a Star Member Latest Breaking News Editorials & Other Articles General Discussion The DU Lounge All Forums Issue Forums Culture Forums Alliance Forums Region Forums Support Forums Help & Search

OKIsItJustMe

(22,126 posts)
Wed May 20, 2026, 04:00 PM 2 hrs ago

Inge Lehmann Discovered Earth's Inner Core In Her Free Time

https://news.ku.dk/lehmann_eng/
She struggled with prejudice and lack of opportunities as a woman in science. But she persisted and ultimately revolutionised our knowledge of Earth.

On a summer’s day in 1932, Inge Lehmann embarks on the journey of a lifetime. The 44-year-old usually spends her summer holidays sweating on Europe's steep mountain sides. But this summer, she's not going anywhere.

She is at her desk in her small, whitewashed cottage on a hilltop in Holte outside Copenhagen, surrounded by maps and cardboard boxes filled with documents. Each box contains data about arrival times and wave strengths from an earthquake at a specific location. One box with data from Tokyo, one from Vienna, one from London.

Slowly but surely, Inge Lehmann follows the earthquake waves through the many layers of Earth on a voyage of discovery into its burning inner core. 5,100 km beneath the surface of Earth, she discovers something no one else has seen before.



After the earthquake in New Zealand, Inge Lehmann discovers something curious: Several seismographs in Europe have registered a few P-waves from the quake, even though they are in the shadow zone. She closely studies multiple seismograms from different locations to map the path of P-waves through Earth's interior. And then she has an idea: When the P-waves from the earthquake travel through Earth's liquid core, some of them hit another core. A hard core that deflects the waves and sends them to the shadow zone, where they otherwise should not arrive.


In Inge Lehmann's time, P-waves and S-waves were observed after an earthquake, as shown here. The dotted lines show the P-waves that Inge Lehmann interpreted as evidence that there had to be an inner core deep within Earth, which deflected certain P-waves and sent them into the area where they would otherwise not have arrived.
Graphics: Frans Wej Petersen

2 replies = new reply since forum marked as read
Highlight: NoneDon't highlight anything 5 newestHighlight 5 most recent replies
Inge Lehmann Discovered Earth's Inner Core In Her Free Time (Original Post) OKIsItJustMe 2 hrs ago OP
Thank you for bringing this to our notice! It looks like a wonderful "deep" read. erronis 1 hr ago #1
You're welcome! OKIsItJustMe 1 hr ago #2

erronis

(24,541 posts)
1. Thank you for bringing this to our notice! It looks like a wonderful "deep" read.
Wed May 20, 2026, 04:48 PM
1 hr ago

And I always like reading about how people have overcome odds to present new information - especially a woman that is going against the "scientific" wisdom of that time.

I have a sister who persevered over years of prejudice and is now quite well known and admired in her field.

Kick in to the DU tip jar?

This week we're running a special pop-up mini fund drive. From Monday through Friday we're going ad-free for all registered members, and we're asking you to kick in to the DU tip jar to support the site and keep us financially healthy.

As a bonus, making a contribution will allow you to leave kudos for another DU member, and at the end of the week we'll recognize the DUers who you think make this community great.

Tell me more...

Latest Discussions»Culture Forums»Science»Inge Lehmann Discovered E...