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D. Physicists Seek to Better Understand the Earth's Core

Narrator: This is Science Today. Determining the melting point of iron is essential to determine temperatures at the boundaries of the Earth's core, as well as the crystal structure of the solid inner core. Various experiments have been conducted to find out, but there wasn't consensus. Now, scientists at the Lawrence Livermore National Laboratory have used what's called a two-stage gas gun to determine the melting point to be just over 87 hundred degrees Fahrenheit. Lab physicist Neil Holmes co-led the study.

Holmes: We're measuring the melting indirectly. What we know is that solids support, basically the same kind of sound waves we see in seismology. And what you see when it melts, there's an abrupt change in velocity and so we're using that as a measure of how the iron melts.

Narrator: Holmes and his colleagues have been trying to measure the temperature for fifteen years.

Holmes: It's a very hard problem it's one of the easiest problems to ask and one of the hardest ones to solve. So a long-term goal of the work in the group is to determine a solidly grounded way to measure the temperature as well.

Narrator: For Science Today, I'm Larissa Branin.