- Earth science
Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the
sciences related to the planet Earth [ [http://wordnet.princeton.edu/perl/webwn?s=earth%20science Wordnet Search: Earth science] ] . It is arguably a special case in planetary science, the Earth being the only known life-bearing planet. There are both reductionistand holistic approaches to Earth science. There are four major disciplines in earth sciences, namely geography, geology, geophysicsand geodesy. These major disciplines use physics, chemistry, biology, chronologyand mathematicsto build a quantitative understanding of the principal areas or "spheres" of the Earth system.It is the study of earth and space.
Earth science generally recognizes 4 spheres, the
lithosphere, the hydrosphere, the atmosphere, and the biosphere[http://www2.cet.edu/ete/hilk4/intro/spheres.html Earth's Spheres] . ©1997-2000. Wheeling Jesuit University/NASA Classroom of the Future. Retrieved November 11 2007.] ; these correspond to rocks, water, air, and life. Some practitioners include, as part of the spheres of the Earth, the cryosphere(corresponding to ice) as a distinct portion of the hydrosphere, as well as the pedosphere(corresponding to soil) as an active and intermixed sphere.
fields of scienceare generally categorized within the geosciences:
Geologydescribes the rocky parts of the Earth's crust (or lithosphere) and its historic development. Major subdisciplines are mineralogyand petrology, geochemistry, geomorphology, paleontology, stratigraphy, structural geology, engineering geologyand sedimentology[Adams 20] Smith 5] .
Geophysicsand Geodesyinvestigate the figure of the Earth, its reaction to forces and its magnetic and gravity fieldsFact|date=November 2007. Geophysicists explore the Earth's coreand mantle as well as the tectonic and seismic activity of the lithosphere [ [http://wordnet.princeton.edu/perl/webwn?s=geodesy Wordnet Search: Geodesy] ] [ [http://www.oceanservice.noaa.gov/education/kits/geodesy/welcome.html NOAA National Ocean Service Education: Geodesy] ] .
Soil sciencecovers the outermost layer of the Earth's crust that is subject to soil formation processes (or pedosphere) [ [http://soil.gsfc.nasa.gov/ped/pedosph.htm Elissa Levine, 2001, The Pedosphere As A Hub] ] . Major subdisciplines include edaphologyand pedology [ [http://jan.ucc.nau.edu/~doetqp-p/courses/env320/lec1/Lec1.html Duane Gardiner, Lecture: Why Study Soils? excerpted from Miller, R.W. & D.T. Gardiner, 1998. Soils in our Environment, 8th Edition] ] .
Oceanographyand hydrology(includes limnology) describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere). Major subdisciplines include hydrogeologyand physical, chemical, and biological oceanographyFact|date=November 2007.
Glaciologycovers the icy parts of the Earth (or cryosphere).
Atmospheric sciencescover the gaseous parts of the Earth (or atmosphere) between the surface and the exosphere(about 1000 km). Major subdisciplines are meteorology, climatology, atmospheric chemistryand atmospheric physics.
* A very important linking sphere is the biosphere, the study of which is
biology. The biosphere consists of all forms of life, from single-celled organisms to pine trees to people. The interactions of Earth's other spheres - lithosphere/geosphere, hydrosphere, atmosphere and/or cryosphere and pedosphere - create the conditions that can support life.
Plate tectonics, mountain ranges, volcanoes, and earthquakes are geological phenomena that can be explained in terms of energy transformations in the Earth's crust. [ [http://okfirst.ocs.ou.edu/train/meteorology/EnergyBudget.html Earth's Energy Budget] ]
Beneath the earth's crust lies the mantle which is heated by the radioactive decay of heavy elements. The mantle is not quite solid and consists of
magmawhich is in a state of semi-perpetual . This convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics. [Simison par. 7] Adams 94,95,100,102] [Smith 13-17,218,G-6] Oldroyd 101,103,104]
Plate tectonics might be thought of as the process by which the earth resurfaces itself. Through a process called "spreading ridges" (or
seafloor spreading), the earth creates new crust by allowing magma underneath the lithosphere to come to the surface where it cools and solidifies--becoming new crust, and through a process called subduction, excess crust is pushed underground--beneath the rest of the lithosphere--where it comes into contact with magma and melts--rejoining the mantle from which it originally came. [Smith 327]
Areas of the crust where new crust is created are called "divergent boundaries", and areas of the crust where it is brought back into the earth are called "convergent boundaries". [Smith 316,323-325] [There is another type of boundary called a
transform boundarywhere plates slide in opposite directions but no new lithospheric material is created or destroyed (Smith 331).] Earthquakesresult from the movement of the lithospheric plates, and they often occur near covergent boundaries where parts of the crust are forced into the earth as part of subduction.Smith 325,326,329] Volcanoesresult primarily from the melting of subducted crust material. Crust material that is forced into the Asthenospheremelts, and some portion of the melted material becomes light enough to rise to the surface--giving birth to volcanoes.
Earth's electromagnet field
electromagnetis a magnet that is created by a current that flows around a soft-iron core. [American 576] The earth has a soft iron core surrounded by semi-liquid materials from the mantle that move in continuous currents around the core; [The earth has a solid iron inner core surrounded by a liquid outer core (Oldroyd 160).] therefore, the earth is an . This is referred to as the dynamo theoryof earth's magnetism.Oldroyd 160] cite web
title=Dynamo Theory and Earth's Magnetic Field.
accessdate=2007-11-17] The fact that earth is an electromagnet helps with the earth's maintenance of an atmosphere suitable for life.
The earth is blanketed by an
atmosphereconsisting of 78.0% nitrogen, 20.9% oxygen, and 1% Argon.Adams 107-108] The atmosphere has five layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere; and 75% of the atmosphere's gases are in the bottom-most layer, the troposphere.
magnetic fieldcreated by mantle's internal motions produces the magnetospherewhich protects the earth's atmosphere from the solar wind. [Adams 21-22] It is theorized that the solar wind would strip away earth's atmosphere in a few million years were it not for the earth's electromagnet.fact|date=November 2007 And since earth is 4.5 billion years old,Smith 183] earth would not have an atmosphere by now if there were no magnetosphere.
The atmosphere is composed of 78%
nitrogenand 21% oxygen. The remaining one percent contains small amounts of other gases including CO2 and water vapors. Water vapors and CO2 allow the earth's atmosphere to catch and hold the sun's energy through a phenomenon called the greenhouse effect. [American 770] This allows earth's surface to be warm enough to have liquid water and support life.
In addition to storing heat, the atmosphere also protects living organisms by shielding the earth's surface from
cosmic rays. Note that the level of protection is high enough to prevent cosmic rays from destroying all life on Earth, yet low enough to aid the mutationsthat have an important role in pushing forward diversity in the biosphere.fact|date=November 2007
Like all other scientists, Earth scientists apply the
scientific method. They formulate hypothesesafter observing events and gathering data about natural phenomena, and then they test hypotheses from such data.
A contemporary idea within earth science is uniformitarianism. Uniformitarianism says that "ancient geologic features are interpreted by understanding active processes that are readily observed".fact|date=June 2008 Simply stated, this means that features of the Earth can be explained by the actions of gradual processes operating over long periods of time; for example, a mountain need not be thought of as having been created in a moment, but instead it may be seen as the result of continuous subduction, causing magma to rise and form continental volcanic arcs.
Partial list of the major Earth Science topics
Lithosphere or geosphere
Geodynamics(see also Tectonics)
Gravimetry(also part of Geodesy)
NASA Earth Science Enterprise
Earth sciences graphics software
List of basic earth science topics
List of geoscience organizations
Structure of the Earth
Glossary of geology terms
* Allaby M., 2008. Dictionary of Earth Sciences, Oxford University Press, ISBN 978-0199211944
* cite book
title=Earth Science: An illustrated guide to science
location=New York NY 10001
* cite book
title=American Heritage dictionary of the English language
location=222 Berkeley Street, Boston, MA 02116
pages=pp. 572, 770
* Korvin G., 1998. Fractal Models in the Earth Sciences, Elsvier, ISBN 978-0444889072
* cite web
title=Earth's Energy Budget
publisher=Oklahoma Climatological Survey
* cite web
title=WordNet Search 3.0
work=WordNet a lexical database for the English language
publisher=Princeton University/Cognitive Science Laboratory /221 Nassau St./ Princeton, NJ 08542
coauthors=Christiane Fellbaum, and Randee Tengi, and Pamela Wakefield, and Rajesh Poddar, and Helen Langone, and Benjamin Haskell
* cite web
title=NOAA National Ocean Service Education: Geodesy
publisher=National Oceanic and Atmospheric Administration
* cite book
title=Earth Cycles: A historical prespective
* cite book
title=Earth Science: Decade by Decade
publisher=Facts on File
location=New York, NY
ids=earth-science history during the 20th century
* cite web
title=The mechanism behind plate tectonics
author=Simison, W. Brian
* cite book
title=How Does the Earth Work?
subtitle=Physical Geology "and the" Process of Science
publisher=Pearson Prentice Hall
location=Upper Saddle River, NJ 07458
* Tarbuck E. J., Lutgens F. K., and Tasa D., 2002. Earth Science, Prentice Hall, ISBN 978-0130353900
* Yang X. S., 2008. Mathematical Modelling for Earth Sciences, Dunedin Academic Press, ISBN 978-1903765920
Wikimedia Foundation. 2010.
Look at other dictionaries:
earth science — noun count or uncount a science that involves studying the Earth, for example geography or GEOLOGY … Usage of the words and phrases in modern English
earth science — n. any of various sciences, as geology or meteorology, dealing with the earth or its components earth scientist n … English World dictionary
earth science — earth .science n [C usually plural] a science, such as ↑geology, which involves the study of the physical world … Dictionary of contemporary English
earth science — noun any of the sciences that deal with the earth or its parts • Hypernyms: ↑natural science • Hyponyms: ↑paleontology, ↑palaeontology, ↑fossilology, ↑geology, ↑meteorology, ↑oceanograph … Useful english dictionary
earth science — UK / US noun [countable/uncountable] Word forms earth science : singular earth science plural earth sciences a science that involves studying the Earth, for example geography or geology … English dictionary
earth science — žemdirbystė statusas T sritis ekologija ir aplinkotyra apibrėžtis Mokslas, tiriantis racionalius žemės naudojimo ir derlingumo didinimo būdus ir priemones. atitikmenys: angl. agriculture; earth science vok. Ackerbau, m; Feldbau, m; Landbau, m;… … Ekologijos terminų aiškinamasis žodynas
earth science — žemdirbystė statusas T sritis ekologija ir aplinkotyra apibrėžtis Žemės ūkio šaka – maistinių, techninių, pašarinių augalų auginimas. atitikmenys: angl. agriculture; earth science vok. Ackerbau, m; Feldbau, m; Landbau, m; Landwirtschaft, f rus.… … Ekologijos terminų aiškinamasis žodynas
earth science — earth′ sci ence n. gel any of various sciences, as geography, geology, or meteorology, that deal with the earth Also called geoscience • Etymology: 1935–40 earth′ sci entist, n … From formal English to slang
earth science — earth scientist. any of various sciences, as geography, geology, or meteorology, that deal with the earth, its composition, or any of its changing aspects. Also called geoscience. [1935 40] * * * … Universalium
earth science — (also earth sciences) noun the branches of science concerned with the physical constitution of the earth and its atmosphere … English new terms dictionary