World Library  
Flag as Inappropriate
Email this Article

Outer core

Article Id: WHEBN0000146249
Reproduction Date:

Title: Outer core  
Author: World Heritage Encyclopedia
Language: English
Subject: Geophysics, Geomagnetic pole, Earth's magnetic field, Francis Birch (geophysicist), Earth
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Outer core

The outer core of the Earth is a liquid layer about 2,300 km (1,400 mi)[1] thick and composed of iron and nickel that lies above Earth's solid inner core and below its mantle. Its outer boundary lies 2,890 km (1,800 mi) beneath Earth's surface. The transition between the inner core and outer core is located approximately 5,150 km (3,200 mi) beneath the Earth's surface.

Properties

The temperature of the outer core ranges from 4,300 K (4,030 °C; 7,280 °F) in the outer regions to 6,000 K (5,730 °C; 10,340 °F) near the inner core. Because of its high temperature, modeling work has shown that the outer core is a low viscosity fluid (about ten times the viscosity of liquid metals at the surface) that convects turbulently.[2] Eddy currents in the nickel iron fluid of the outer core are believed to influence the Earth's magnetic field. The average magnetic field strength in the Earth's outer core was measured to be 2.5 millitesla, 50 times stronger than the magnetic field at the surface.[3][4] The outer core is not under enough pressure to be solid, so it is liquid even though it has a composition similar to that of the inner core. Sulfur and oxygen could also be present in the outer core.[5]

As heat is transferred outward toward the mantle, the net trend is for the inner boundary of the liquid region to freeze, causing the solid inner core to grow. This growth rate is estimated to be 1 mm per year.[6]

See also

References

  1. ^ http://education.nationalgeographic.com.au/education/encyclopedia/core/?ar_a=1
  2. ^
  3. ^ First Measurement Of Magnetic Field Inside Earth's Core. Science20.com. Retrieved on 2012-01-27.
  4. ^
  5. ^
  6. ^

External links

  • Outer core from universetoday.com
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.