By measuring seismic waves traveling through Earth, researchers have developed a solid understanding of its basic internal structure. So, what's inside Earth? Planet Earth is broadly composed of a ...

to use observations at or near the surface of Earth to constrain ideas about its deep structure and dynamics. Better communication and cross-education among these disciplines is key to progress.

Earth's diameter is about 7,900 miles. The planet's internal structure comprises four layers: a rocky crust on the outside, then a rocky mantle, an outer core made of magma and a solid inner core.

The Moon and Mars cannot sustain Earth's population of humans and other organisms. Earth's internal structure Earth's core is about 4,400 miles (7,100 km) wide, slightly larger than half the Earth ...