Stories tagged radioactive decay

Gravitational compression

Will Earth ever freeze?: Internal radioactive decay is expected to keep Earth heated for billions of years.
Courtesy NASA In its beginning, the Earth was so hot that it was entirely melted. That heat was generated because of gravitational compression. As gravity pulls materials in outer space towards each other they are compressed. When atoms and molecules are squeezed together they generate heat. Matter at the earth's center is very compressed; in fact, Earth is the densest planet in the Solar system.

Gravitational sorting

Penn State professor of geosciences, Chris Marone, feels that the original heat from that molten earth is only about 5 to 10 percent of the total heat within our planet. Another source of heat is from gravitational sorting.

In a gravitational sorting process called differentiation, the denser, heavier parts were drawn to the center, and the less dense areas were displaced outwards. The friction created by this process generated considerable heat, which, like the original heat, still has not fully dissipated.

Latent heat

Another source of heat is latent heat. When material in the center of the Earth changes from a liquid to a solid, heat is released. The solidified material also expands, which increases the pressure, thereby increasing the temperature. "The inner core is becoming larger by about a centimeter every thousand years," Marone says.

Almost all Earth's heat comes from radioactive decay

Marone says, the vast majority of the heat in Earth's interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. The amount of heat caused by this radiation is almost the same as the total heat measured leaving the Earth.

Source: Penn State University Live

Tags : earth, earth science, Chris Marone, Penn State, geosciences, radioactive decay

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