“You should know how many incompetent men I had to compete with —
in vain”
Inge Lehmann.

Quips aside, Inge Lehmann was a pioneering seismologist who discovered that the Earth has both an inner and an outer core. On Wednesday, May 13, Google honored her 127th birthday with a new animated Doodle.

Form a profile of Lehmann by the American Museum of Natural History:

In 1929 a large earthquake occurred near New Zealand. Danish seismologist Inge Lehmann “the only Danish seismologist,” as she once referred to herself—studied the shock waves and was puzzled by what she saw. A few P-waves, which should have been deflected by the core, were in fact recorded at seismic stations. Lehmann theorized that these waves had traveled some distance into the core and then bounced off some kind of boundary. Her interpretation of this data was the foundation of a 1936 paper in which she theorized that Earth’s center consisted of two parts: a solid inner core surrounded by a liquid outer core, separated by what has come to be called the Lehmann Discontinuity. Lehmann’s hypothesis was confirmed in 1970 when more sensitive seismographs detected waves deflecting off this solid core.

…A critical and independent thinker, Lehmann subsequently established herself as an authority on the structure of the upper mantle. She conducted extensive research in other countries, benefiting from an increased global interest in seismology for the surveillance of clandestine nuclear explosions. When Lehmann received the William Bowie medal in 1971, the highest honor of the American Geophysical Union, she was described as “the master of a black art for which no amount of computerizing is likely to be a complete substitute.” Lehmann lived to be 105.

To read more about P-waves and for some illustrations, see the page
about Lehmann at amnh.org