How Is the Earth Like an Onion?

If you cut an onion across, you’ll find a series of layers surrounding a central core. A cross-section of our planet would show a similar structure.

Studies of earthquakes by geologists, scientists who study the earth, reveal that the earth is made up of three layers: the crust, the mantle, and the core.

The crust, the “skin” of the earth, consists of soil, water, and rock. Its thickness varies from 5 miles under the oceans to 20 miles under land. Some of the deepest parts of the crust may reach temperatures of 1,600°F. At this temperature, it is hot enough to melt rocks.

The next layer, the mantle, is a thick layer of rock, about 1,800 miles deep. The deepest parts here may reach temperatures of 4,000°F.

The core is actually made up of two layers, an outer core and an inner core. The outer core, 1,400 miles thick, has an average temperature of 6,500°F, and is believed to be mostly liquid, melted iron and nickel.

The ball-like inner core is actually the center of the earth. Its 800-mile thickness is believed to be solid iron and nickel. The temperature here may reach as high as 9,000°F., the highest of any layer, but the inner core remains solid rather than melting because of the tremendous weight and pressure the earth above exerts upon it.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

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