Earth's inner core
The inner core is the very center of the Earth, and the hottest part of the planet. The inner core was discovered by Inge Lehmann in 1929, using seismology. Lehmann was studying a large New Zealand earthquake. An earthquake makes vibrations which move through the inside of the Earth. The vibrations Lehmann studied seemed to be moving across something solid in the center of the planet. She called this the inner core. She wrote about it for many years, but it was not proved to exist until 1970.
The inner core is about 1,220 km (760 ml) in diameter, and more than 5,000 kilometers below the earth's surface. It is believed to be made of molten (melted) iron and nickel. Due to the pressure at the centre of the Earth, the inner core does not move like a liquid.
The temperature of the inner core is estimated as 5,700 K (5,430 °C; 9,800 °F). The pressure in Earth's inner core is about 3,500,000 atmospheres. Iron can only be solid at such high temperatures because its melting temperature increases dramatically at such pressures.
Other websites[change | change source]
- How Inge Lehmann discovered the inner core. (complex English).
References[change | change source]
- D. Alfè; M. Gillan and G. D. Price (January 30, 2002). "Composition and temperature of the Earth’s core constrained by combining ab initio calculations and seismic data" (PDF). Earth and Planetary Science Letters 195 (1-2): 91–98. doi:10.1016/S0012-821X(01)00568-4. http://www.es.ucl.ac.uk/people/d-price/papers/138.pdf.
- David. R. Lide, ed. (2006-2007). CRC Handbook of Chemistry and Physics (87th ed.). pp. 14–13. http://hbcpnetbase.com/.
- Anneli Aitta (2006-12-01). "Iron melting curve with a tricritical point". Journal of Statistical Mechanics: Theory and Experiment (iop) 2006 (12): 12015–12030. doi:10.1088/1742-5468/2006/12/P12015. http://stacks.iop.org/JSTAT/2006/P12015. or see preprints http://arxiv.org/pdf/cond-mat/0701283 , http://arxiv.org/pdf/0807.0187 .