Today in Mighty Girl history, Danish seismologist and geophysicist Inge Lehmann -- who first discovered that the Earth has a solid core -- was born in 1888. Lehmann revolutionized our understanding of the Earth’s composition by mathematically analyzing seismic waves from earthquakes, proving that our planet has a solid inner core inside of a molten outer core. Her “exacting scrutiny of seismic records” was hailed by Francis Birch of the American Geophysical Union, who called her “a master of a black art for which no amount of computerization is likely to be a complete substitute.”
Lehmann was studying an earthquake in New Zealand in 1929 when she first discovered that the seismic waves, called P waves, appeared to be bouncing off of a boundary at the center of the Earth -- contradicting the prevailing theory that the Earth’s core was liquid. In a 1936 paper, Lehmann laid out mathematical proof that the Earth’s core was solid; within a few years, her interpretation was accepted by other leading seismologists. She continued doing research throughout her life, even years after her official retirement, and in 1959, she discovered another anomaly in how seismic waves travel through the Earth’s mantle, the Lehmann discontinuity, which seismologists are trying to explain today.
She received many awards and honors for her work, and published her last scientific paper at the age of 99; she died in 1993 at the age of 104. In 1997, the American Geophysical Union established the Inge Lehmann Medal to honor "outstanding contributions to the understanding of the structure, composition, and dynamics of the Earth’s mantle and core." She is still remembered for her incredible work ethic, her tremendous mathematical gifts, and for her refusal to believe that her contributions were less valuable because she was a woman. As she famously declared, “You should know how many incompetent men I had to compete with -- in vain!”
Inge Lehmann is one of many groundbreaking female scientists featured in the excellent book “Headstrong: 52 Women Who Changed Science -- and the World,” recommended for teens and adults at http://www.amightygirl.com/headstrong-52-women
To encourage your own Mighty Girl's love of math, check out our new blog post, “Add It Up! Top 30 Math Toys for Mighty Girls,” at http://www.amightygirl.com/blog?p=12180
For books for children and teens starring girls who love science and math, check out our blog post, "Ignite Her Curiosity: 25 Books Starring Science-Loving Mighty Girls," at http://www.amightygirl.com/blog?p=10940
And, for many toys to help kids learn more about the world, check out our "Natural World" toy section at http://amgrl.co/22386qu