Big thanks to Sharon Hill, who kindly served as our geoscience proofreader for the script of this episode. In addition to her geology work in Pennsylvania, Hill maintains the site www.DoubtfulNews.com, “an aggregator of strange and questionable claims in the media (not necessarily all doubtful or harmful) with a dose of critical thinking commentary.” Thanks, Sharon, for helping us get things right, and for your daily work in advancing scientific literacy in the public sphere!

Sources:

http://www.livescience.com/33490-how-journey-center-earth.html

https://www.khanacademy.org/science/cosmology-and-astronomy/earth-history-topic/plate-techtonics/v/how-we-know-about-the-earth-s-core

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

http://www.amnh.org/education/resources/rfl/web/essaybooks/earth/p_lehmann.html

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

http://bigthink.com/eruptions/drilling-into-the-planet-why-we-want-to-sample-the-mantle-and-why-we-already-have

http://www.natureworldnews.com/articles/1606/20130426/earths-core-temperature-hellish-6-000-degrees-celsius-new-study.htm

http://www.popularmechanics.com/science/environment/articles/a7749/how-do-we-know-whats-in-the-earths-core-pm-explains-9750875/

http://www.extremetech.com/extreme/154357-earths-core-is-much-hotter-than-previously-thought-hotter-than-the-surface-of-the-sun

http://www.seismosoc.org/publications/SRL/SRL_78/srl_78-6_hs.html