UNIVERSE
PLANETARY INTERIORS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Volcanic eruptions can bring melted rock onto the surface that cools into new rock
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Seismic waves that pass through Earth bring mantle rocks to the surface
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Certain meteorites bombarded Earth and may represent the composition of the mantle
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Volcanic eruptions can bring solid chunks of rock from Earth’s mantle to Earth’s surface
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Detailed explanation-1: -Scientists know that the mantle is made of rock based on evidence from seismic waves, heat flow, and meteorites. The properties fit the ultramafic rock peridotite, which is made of the iron-and magnesium-rich silicate minerals (Figure below). Peridotite is rarely found at Earth’s surface.
Detailed explanation-2: -Scientists can infer a lot about the mantle, even without a sample. The speeds and paths of earthquake-generated seismic waves passing through the planet provide insight about the density, viscosity and overall characteristics of the mantle, as well as how those properties vary from place to place.
Detailed explanation-3: -By tracking seismic waves, scientists have learned what makes up the planet’s interior (figure 2). P-waves slow down at the mantle core boundary, so we know the outer core is less rigid than the mantle. S-waves disappear at the mantle core boundary, so the outer core is liquid.
Detailed explanation-4: -So scientists rely on seismic waves-shock waves generated by earthquakes and explosions that travel through Earth and across its surface-to reveal the structure of the interior of the planet. Thousands of earthquakes occur every year, and each one provides a fleeting glimpse of the Earth’s interior.