Final answer:
Scientists determined that the outer core is a liquid through the analysis of seismic waves and magma chemistry, as well as direct detection of energy from seismic waves that travel only through liquids.
Step-by-step explanation:
Scientists determined that the outer core is a liquid through various methods. One way is by analyzing seismic waves that travel through Earth. Certain seismic waves that only travel through solids produce shadow zones in different parts of the globe, indicating that there is a region where these waves cannot pass through, suggesting the presence of a liquid outer core. Another method is by studying magma from deep within Earth's surface. Analysis of this magma showed that it is chemically different from magma in Earth's mantle and crust, further supporting the idea of a liquid outer core. Additionally, scientists have detected energy from certain seismic waves that only travel through liquids deep within Earth, providing direct evidence for the presence of a liquid outer core.
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