Core of the Earth

the central geosphere, with a radius of about 3,470 km. The existence of the earth’s core was established in 1897 by the German seismologist E. Wiechert. The depth of the core’s boundary, 2,900 km, was determined in 1910 by the American geophysicist B. Gutenberg. Various hypotheses have been advanced regarding the composition and origin of the core of the earth.

According to some scientists, the earth’s core may be composed of iron, together with an admixture of nickel, sulfur, silicon, or other elements. According to others, it may consist of iron oxides that acquire metallic properties under high pressure.

The hypothesis that the earth’s core was formed by gravitational differentiation of the primordial earth either during the growth of the planet or later was first suggested by the Norwegian geophysicist V. M. Goldschmidt in 1922. The hypothesis that an iron core formed in the protoplanetary nebula was advanced in 1944 by the German scientist A. Eucken and again in the 1960’s and the 1970’s by the American scientist E. Orowan and the Soviet scientist A. P. Vinogradov. (See alsoEARTH.)

REFERENCE

Vitiazev, A. V., E. N. Liustikh, and V. V. Nikolaichik. “Problema obrazovaniia iadra i mantii Zemli.” Izv. AN SSSR: Ser. Fizika Zemli, 1977, no. 8.

单词	core of the earth
释义	Core of the Earth Core of the Earth the central geosphere, with a radius of about 3,470 km. The existence of the earth’s core was established in 1897 by the German seismologist E. Wiechert. The depth of the core’s boundary, 2,900 km, was determined in 1910 by the American geophysicist B. Gutenberg. Various hypotheses have been advanced regarding the composition and origin of the core of the earth. According to some scientists, the earth’s core may be composed of iron, together with an admixture of nickel, sulfur, silicon, or other elements. According to others, it may consist of iron oxides that acquire metallic properties under high pressure. The hypothesis that the earth’s core was formed by gravitational differentiation of the primordial earth either during the growth of the planet or later was first suggested by the Norwegian geophysicist V. M. Goldschmidt in 1922. The hypothesis that an iron core formed in the protoplanetary nebula was advanced in 1944 by the German scientist A. Eucken and again in the 1960’s and the 1970’s by the American scientist E. Orowan and the Soviet scientist A. P. Vinogradov. (See alsoEARTH.) REFERENCE Vitiazev, A. V., E. N. Liustikh, and V. V. Nikolaichik. “Problema obrazovaniia iadra i mantii Zemli.” Izv. AN SSSR: Ser. Fizika Zemli, 1977, no. 8.
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