Difference between revisions 1863059 and 1875257 on enwikiversity

[[Image:Ice cap.jpg|thumb|right|2050px|This is an aerial image of the ice cap on Ellesmere Island, Canada. Credit: National Snow and Ice Data Center.]]
'''Earth''' is a rocky astronomical object, a liquid object, a gaseous object, and a plasma object.
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==Astronomy==
{{main|Draft:Astronomy}}
[[Image:Greenland 42.74746W 71.57394N.jpg|thumb|right|2050px|Satellite composite image shows the ice sheet of Greenland. Credit: NASA.]]
At the right is a satellite composite image of the ice sheet over Greenland.
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==Radiation astronomy==
{{main|Draft:Radiation astronomy}}
[[Image:Earth-moon.jpg|thumb|left|2050px|This view of the rising Earth greeted the Apollo 8 astronauts as they came from behind the Moon after the lunar orbit insertion burn. Credit: NASA.]]
"Energetic photons, ions and electrons from the solar wind, together with galactic and extragalactic cosmic rays, constantly bombard surfaces of planets, planetary satellites, dust particles, comets and asteroids."<ref name=Madey>{{ cite journal
|author=Theodore E. Madey, Robert E. Johnson, Thom M. Orlando
|title=Far-out surface science: radiation-induced surface processes in the solar system
|journal=Surface Science
|month=March
|year=2002
|volume=500
|issue=1-3
|pages=838-58
|url=http://www.physics.rutgers.edu/~madey/Publications/Full_Publications/PDF/madey_SS_2002.pdf
|arxiv=
|bibcode=
|doi=10.1016/S0039-6028(01)01556-4
|pmid=
|accessdate=2012-02-09 }}</ref> "[I]nterplanetary space ... is a stormy and sometimes very violent environment permeated by energetic particles and radiation constantly emanating from the Sun."<ref name=Madey/>
{{clear}}

==Planets==
{{main|Draft:Planets}}
[[Image:Heic0821e.jpg|thumb|right|2050px|This annotated image shows key features of the Fomalhaut system, including the newly discovered planet Fomalhaut b, and the dust ring. Credit: Credit: NASA, ESA, and Z. Levay (STScI).]]
'''Def.''' "a celestial body that

(a) is in orbit around the Sun,

(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and

(contracted; show full)|month=11 November
|year=2005
|url=https://en.wiktionary.org/wiki/Earth
|accessdate=2016-02-06 }}</ref> is called '''Earth'''.

==Geognosy==
{{main|Earth/Geognosy|Geognosy}}
[[Image:Slice_earth.svg|thumb|2
050px|right|This diagram is a theoretical interior for the rocky object called the [[Earth]] by its hominid inhabitants. Credit: [[commons:User:Dake|Dake]].]]
[[Image:Earthquake wave paths.svg|thumb|right|2050px|Seismic velocities and boundaries are diagrammed for the interior of the [[Earth]] sampled by seismic waves. Credit: .]]
[[Image:Earth-crust-cutaway-English-Large label.PNG|thumb|left|2050px|This is a cutaway illustration of the interior of the [[Earth]]. Credit: Washiucho and [[commons:User:Brews ohare|Brews ohare]].]]
The diagram on the right is a theoretical interior for the Earth. Some of the depths and likely constitution of successive spheres are based on the results of [[geoseismology]]

(contracted; show full)m must also be determined. This requires physical theory for thermal conduction and convection and the heat contribution of [radionuclides] radioactive elements. The main model for the radial structure of the interior of the Earth is the Preliminary Reference Earth Model (PREM). Some parts of this model have been updated by recent findings in mineral physics (see post-perovskite) and supplemented by seismic tomography.
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==Crusts==
{{main|Earth/Crusts|Crusts}}
[[Image:San Andreas.jpg|thumb|right|2
050px|The image shows a portion of the San Andreas Fault in California USA on Earth. Credit: Robert E. Wallace, USGS.]]
Using [[airborne astronomy]], the image on the right shows a portion of the San Andreas Fault in California USA.
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==Cryospheres==
{{main|Earth/Cryospheres|Cryospheres}}
[[Image:Ridging 0.jpg|thumb|right|2050px|The photo shows ridged sea ice. Credit: Don Perovich, U.S. Army Cold Regions Research and Engineering Laboratory.]]
[[Image:Cryosphere Fuller Projection.png|thumb|center|400px|Overview of the Cryosphere and its larger components, from the [http://maps.grida.no/go/graphic/cryosphere UN Environment Programme Global Outlook for Ice and Snow]. Credit: .]]
[[Image:Antarctica 6400px from Blue Marble.jpg|thumb|right|2050px|A satellite composite image shows the ice sheet of Antarctica Credit: [[commons:User:Dave Pape|Dave Pape]].]]
The '''cryosphere''' is a term which collectively describes the portions of [an astronomical object's] surface where [[water]] is in solid form, including sea ice, lake ice, river ice, snow cover, [[glaciers]], ice caps and ice sheets, and frozen ground (which includes permafrost). Thus there [may be] a wide overlap with [a] hydrosphere. The cryosphere is an in(contracted; show full)
|accessdate=2013-05-14 }}</ref>

"The inner core, on average, rotates eastward. At the speeds it travels, it might, on average, complete a revolution every 750 to 1,440 years. However, these speeds appear unstable, which makes it uncertain just how long it actually takes to finish a turn on its axis".<ref name=Choi/>
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==Object astronomy==
{{main|Radiation astronomy/Objects|Object astronomy}}
[[Image:Shuga.jpg|thumb|right|2
050px|Here is shuga forming on a shoreline. Credit: Antarctic Sea-Ice Processes and Climate program (ASPeCt).]]
'''Def.''' "a body of unfrozen ground, that is perennially cryotic (T < 0 degrees Celsius) and entirely surrounded by perennially frozen ground"<ref name=Beitler/> is called an '''isolated cryopeg'''.

'''Def.''' "a form of new ice, composed of spongy, white lumps a few cm across, that tend to form in rough seas; they resemble slushy snow balls"<ref name=Beitler/> is called '''shuga'''.
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==Emissions==
{{main|Radiation astronomy/Emissions|Emissions}}
[[Image:Calving.jpg|thumb|right|2050px|An ice pinnacle separates from Perito Moreno Glacier. Credit: Martyn Clark.]]
'''Def.''' a "process by which ice breaks off a glacier's terminus"<ref name=Beitler/> is called '''calving'''.
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==Absorptions==
{{main|Radiation astronomy/Absorptions|Absorption astronomy|Absorptions}}
[[Image:Spectrum of blue sky.svg|thumb|right|A spectrum is taken of blue sky clearly showing solar [[w:Fraunhofer lines|Fraunhofer lines]] and atmospheric water absorption band. Credit: .]]
[[Image:Cirque.jpg|thumb|right|2050px|This show a cirque on Cirque Mountain in the Torngat Mountains, Newfoundland, Canada. Credit: Hazen Russel, Natural Resources Canada, Terrain Sciences Division, Geological Survey of Canada.]]
"[P]referential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon".<ref name=Bohren>{{ cite book
|url=http://homepages.wmich.edu/%7Ekorista/atmospheric_optics.pdf
|title=Atmospheric Optics
|author=Craig F. Bohren }}</ref>

'''Def.''' a "bowl shape or amphitheater usually sculpted out of the mountain terrain by a ... glacier"<ref name=Beitler/> is called a '''cirque'''.

The image at the right shows a cirque "on Cirque Mountain in the Torngat Mountains, Newfoundland, Canada."<ref name=Beitler/>
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==Meteors==
{{main|Radiation astronomy/Meteors|Meteor astronomy}}
[[Image:Meteor burst.jpg|thumb|right|2050px|This picture is of the Alpha-Monocerotid meteor outburst in 1995. It is a timed exposure where the meteors have actually occurred several seconds to several minutes apart. Credit: NASA Ames Research Center/S. Molau and P. Jenniskens.]]
[[Image:Clouds and the mountain.JPG|thumb|right|2050px|Here at Réunion is an example that some of those white puffy objects in the sky may be quite close by. Credit: [[commons:User:B.navez|B.navez]].]]
[[Image:Cirrus floccus and Cirrus spissatus at sunrise.jpg|thumb|right|180px|Cirrus clouds never seem to touch any mountain. Yet sunrise reveals they are closer to the ground than the Sun. Credit: Simon Eugster.]]
[[Image:Regnbyge.jpg|thumb|left|This image shows a late-summer rainstorm in Denmark. The nearly black color of the cloud's base indicates the foreground cloud is probably cumulonimbus. Credit: [[commons:User:Malene|Malene Thyssen]].]]
[[Image:Glacial icefall.jpg|thumb|right|2050px|This is an image of icefalls on three parallel glaciers. Credit: Tom Lowell, University of Cincinnati.]]
[[Image:Glacier table.jpg|thumb|left|2050px|Talefre Glacier on Mont Blanc Massif in the European Alps sported a prominent glacier table when this undated photograph was taken. Credit: Cairrar.]]
(contracted; show full)==Gamma rays==
{{main|Radiation astronomy/Gamma rays|Gamma-ray astronomy}}

The Earth's atmosphere is a relatively bright source of gamma rays produced in interactions of ordinary cosmic ray protons with air atoms.

==X-rays==
{{main|Radiation astronomy/X-rays|X-rays}}
[[Image:Earthxray polar.jpg|thumb|left|2
050px|This image is a composite of the first picture of the Earth in X-rays over a diagram of the Earth below. Credit: NASA, Ruth Netting.]]
[[Image:X-ray radiograph.jpg|thumb|right|2050px|This shows a photograph and X-radiograph of part of core D4 illustrating fine laminations. Credit: Robert Gilbert, Niels Nielsen, Henrik Möller, Joseph R. Desloges, and Morten Rasch.]]
[[Image:X-ray of core 2.jpg|thumb|left|2050px|Concentration of gravel particles (>2 mm diameter) assessed from X-radiographs (inset shows example from core D20) are inferred to be dominantly ice-rafted. Credit: Robert Gilbert, Niels Nielsen, Henrik Möller, Joseph R. Desloges, and Morten Rasch.]]
The Earth is a known astronomical object. It is usually not thought of as an X-ray source.

(contracted; show full)radiographs [compared to distal sediments as imaged on the left for core D20]. These consist both of the subtle differences in the fine-grained sediments on a millimetre scale, and of the sand layers up to 8 cm thick representing more energetic processes (Ó Cofaigh and Dowdeswell, 2001). Both are a response to greater sediment input to the fjord."<ref name=Gilbert/>
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==Opticals==
{{main|Radiation astronomy/Opticals|Optical astronomy}}
[[Image:Earth-DSCOVR-20150706-IFV.jpg|thumb|right|2
050px|Earth is seen on July 6, 2015 from a distance of one million miles by a NASA scientific camera. Credit: NASA.]]
[[Image:Spectral reflectance curves.jpg|thumb|left|2050px|The figure contains spectral reflectance curves for snow and ice in different formation stages. Credit: Jan-Gunnar Winther.]]
"A NASA camera on the Deep Space Climate Observatory (DSCOVR) satellite has returned its first view of the entire sunlit side of Earth [on the right] from one million miles away."<ref name=Cole>{{ cite book
|author=Steve Cole and Rob Gutro
|title=NASA Satellite Camera Provides “EPIC” View of Earth
|publisher=NASA
|location=Washington, DC USA
|month=20 July
(contracted; show full)
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==Visuals==
{{main|Radiation astronomy/Visuals|Visual astronomy}}
[[Image:Earth and Moon from Mars PIA04531.jpg|thumb|right|140px|The Earth and Moon is imaged by the [[w:Mars Global Surveyor|Mars Global Surveyor]] on May 8, 2003, at 12:59:58 UTC.]]
[[Image:NASA-Apollo8-Dec24-Earthrise.jpg|thumb|left|2
050px|This view of the rising Earth greeted the Apollo 8 astronauts as they came from behind the Moon after the lunar orbit insertion burn. Credit: NASA.]]
[[Image:Earth in vivid colors 1.jpg|thumb|right|2050px|This true-color image shows North and South America as they would appear from space 35,000 km (22,000 miles) above the Earth. Credit: Reto Stöckli, Nazmi El Saleous, and Marit Jentoft-Nilsen, NASA GSFC.]]
[[Image:Crevasse 1916.jpg|thumb|right|2050px|Explorers examine a crevasse on Lyman Glacier in 1916. Credit: United States Forest Service.]]
[[Image:Crevasse.jpg|thumb|left|2050px|A crevasse in Langjökull glacier created by water drilling a hole tens of meters deep into the glacier ice. Credit: [http://www.flickr.com/people/62223880@N00 Ville Miettinen].]]
For those observers looking toward the Earth from another location such as near the Moon in the photograph at above right, it seems that the Earth is a natural object. On the Earth 384,000 km away, the sunset terminator bisects [[Africa]].

(contracted; show full)'''Def.''' an "open fissure in the glacier surface"<ref name=Beitler/> is called a '''crevasse'''.

The crevasse in the image at the right is in Lyman Glacier in 1916. The one on the left is in Langjökull glacier, Iceland, on 29 July 2006.
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==Violets==
{{main|Radiation astronomy/Violets|Violet astronomy}}
[[Image:Glacial trough.jpg|thumb|right|2
050px|Western Brook glacial trough, Newfoundland, Canada, is imaged. Credit: Natural Resources Canada, Terrain Sciences Division, Geological Survey of Canada.]]
'''Def.''' "a large u-shaped valley formed from a v-shaped valley by glacial erosion"<ref name=Beitler/> is called a '''glacial trough'''.

"The sheer walls of this glacial trough [Western Brook glacial trough, Newfoundland, Canada, at the right] soar up to 700 m high, and the glacial basin is 500 m deep in places."<ref name=Beitler/>
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==Blues==
{{main|Radiation astronomy/Blues|Blue astronomy}}
[[Image:Top of Atmosphere.jpg|thumb|2050px|right|The [[Earth]] has a blue halo when seen from space. Credit: NASA Earth Observatory.]]
[[Image:Holmengrå2.JPG|thumb|right|2050px|The Earth can have a blue sky and a blue ocean. Credit: [[commons:User:Frokor|Frokor]].]]
[[Image:Fast ice.jpg|thumb|right|2050px|This is land fast ice. Credit: Michael Van Woert, National Oceanic and Atmospheric Administration/Department of Commerce.]]
'''Def.''' "[t]he gases surrounding the Earth or any astronomical body"<ref name=AtmosphereWikt>{{ cite book
|author=[[wikt:User:212.159.113.112|212.159.113.112]]
|title=atmosphere
|publisher=Wikimedia Foundation, Inc
|location=San Francisco, California
|month=6 May
|year=2003
|url=https://en.wiktionary.org/wiki/atmosphere
|accessdate=2016-02-06 }}</ref> is called an '''atmosphere'''.

Atmospheric [[w:gas|gas]]es scatter blue light more than other wavelengths, giving the [[Earth]] a blue halo when seen from space, as shown in the image at right.

'''Def.''' "ice that is anchored to the shore or ocean bottom, typically over shallow ocean shelves at continental margins; fast ice is defined by the fact that it does not move with the winds or currents"<ref name=Beitler/> is called '''fast ice'''.

The image at the right shows land fast ice.
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==Cyans==
{{main|Radiation astronomy/Cyans|Cyan astronomy}}
[[Image:Bhutan magenta cyan image 2.jpg|thumb|right|2050px|A composite red-cyan anaglyph image displays the rectified Hexagon stereo pair. Credit: Josh Maurer and Summer Rupper.]]
[[Image:Bhutan stereo disparity map.jpg|thumb|left|2050px|This stereo disparity map is computed using the semi-global block matching algorithm. Credit: Josh Maurer and Summer Rupper.]]
[[Image:Landsat Bhutan panachromatic.jpg|thumb|right|2050px|This is a Landsat panchromatic image showing the study region in Bhutan/China, with upper left inset showing the Kingdom of Bhutan in red outline. Credit: Josh Maurer and Summer Rupper.]]
(contracted; show full)The image at the lower right is a Landsat panchromatic image of the study region in Bhutan/China, with an upper left inset of the Kingdom of Bhutan in red outline.<ref name=Maurer/>

"Temporal changes in area and volume of glaciers and lakes are of interest in this region to better understand the effect of dwindling glacial ice on water resources."<ref name=Maurer/>
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==Greens==
{{main|Radiation astronomy/Greens|Green astronomy}}
[[image:ThufurGlossary.jpg|thumb|right|2
050px|These big lumps in the ground are called thufur. Credit: Reinhold Richter.]]
'''Def.''' "perennial hummocks formed in either the active layer in permafrost areas, or in the seasonally frozen ground in non-permafrost areas, during freezing of the ground"<ref name=Beitler/> is called '''thufur'''.
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==Yellows==
{{main|Radiation astronomy/Yellows|Yellow astronomy}}
[[Image:Glider.jpg|thumb|right|2050px|Photo of the glacier basin taken from a glider shows the yellow Sahara-dust layer melting out in the mid-elevation range of the glacier. Credit: Christina Rothenbühler.]]
In the photograph at the right, Piz Bernina is the highest mountain of the region. Note the yellow Sahara-dust layer melting out in the mid-elevation range of the glacier.<ref name=StaffUUNL>{{ cite book
|author=StaffUUNL
|title=Location and scenery
|publisher=Institute for Marine and Atmospheric Research
|location=
|month=September
|year=2014
|url=http://www.staff.science.uu.nl/~oerle102/site_Mort/menu_1.html
|accessdate=2014-09-26 }}</ref>

"The Morteratschgletscher is located in the Bernina Alps, in the Swiss province ("Kanton") Graubuenden, close to Sankt Moritz."<ref name=StaffUUNL/>
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==Oranges==
{{main|Radiation astronomy/Oranges|Orange astronomy}}
[[Image:Glacial grooves.jpg|thumb|right|2050px|Glacial grooves are caused by erosion of limestone bedrock from the Wisconsin glaciation at Kelleys Island. Credit: [[w:User:Rmhermen|Rmhermen]].]]
Although limestone is usually light gray to white depending on impurities, the heavy glacial grooves and the limestone cross section in the image at the right are brown.
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==Reds==
{{main|Radiation astronomy/Reds|Red astronomy}}
[[Image:Grl16731-fig-0001.png|thumb|right|2050px|A: Back trajectories are reconstructed using the NOAA ARL Website (www.arl.noaa.gov/ready/) and CDC1 meteorological data. B: Backward trajectory is plotted ending at 06:00 UTC, on March 6, 1990. Credit: Francis E. Grousset, Paul Ginoux, Aloys Bory, and Pierre E. Biscaye.]]
(contracted; show full)t;Nd</sub>(o) ≈ −20) such as those observed in the Mauritania Archean provinces [Grousset et al., 1998]. When comparing the data obtained on the particles sampled in Alpine and Pyrenean snows, to those of the isotopic composition of the different dust fields of North Africa, it appears that the dusts reveal generally a North African origin."<ref name=Grousset/>
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==Infrareds==
{{main|Radiation astronomy/Infrareds|Infrared astronomy}}
[[Image:Thematic Mapper image.jpg|thumb|right|2
050px|This is a Landsat Thematic Mapper TM Bands 2, 4 and 5 composite image recorded on 7 August 1987 of several glaciers. Credit: Jan-Gunnar Winther.]]
(contracted; show full)albedo as the snow metamorphoses, i.e. the grain size increases. The visible albedo is little affected by the variation of grain size. Clouds affect the snow albedo by introducing a spectral shift to the incoming radiation. It is shown that the integrated snow albedo (370-900 nm) increases by 7% due to the change from clear sky to overcast weather."<ref name=Winther/>
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==Microwaves==
{{main|Radiation astronomy/Microwaves|Microwave astronomy}}
[[Image:Grl18577-fig-0001.png|thumb|right|2
050px|(a) The probability is for of a pixel melting at least as many times as observed during the 1995, 1998 and 2002 melt seasons given the last 25 years of melt observations. (b) Melt extent is for 2002: Pixels are color coded for number of melt days during the season. (c) Slopes of the trend lines are fit to the areas observed to melt between April and November from 1979 to 2003. Credit: K. Steffen, S. V. Nghiem, R. Huff, and G. Neumann.]]
[[Image:Grl18577-fig-0002.png|thumb|left|2050px|Half-decade records for ETH/CU Camp station: (a) Top panel is for QSCAT backscatter, (b) middle panel for QSCAT diurnal signature, and (c) bottom panel for air temperature measured at the AWS site. Credit: K. Steffen, S. V. Nghiem, R. Huff, and G. Neumann.]]
[[Image:Grl18577-fig-0003.png|thumb|right|2050px|QSCAT melt maps are shown on the climatological peak-melt day (1 August). Red color represents current active melt areas, light blue is for areas that have melted but currently refreeze, white is for areas that will melt later, and magenta is for areas that do not experience any melt throughout the melt season. The dark blue color surrounding Greenland is the ocean mask. Credit: K. Steffen, S. V. Nghiem, R. Huff, and G. Neumann.]]
[[Image:Grl18577-fig-0004.png|thumb|left|2050px|QSCAT maps of number of melt days (violet to red for 1 to 31 days) in 2000–2003 with the overlaid black contours representing melt extent derived from PM data are shown. Credit: K. Steffen, S. V. Nghiem, R. Huff, and G. Neumann.]]
(contracted; show full)
==Radars==
{{main|Radiation astronomy/Radars|Radar astronomy}}
Numerous airborne and spacecraft radars have mapped the entire planet, for various purposes. One example is the Shuttle Radar Topography Mission, which mapped the entire Earth at 30 m resolution.

==Gaseous objects==
{{main|Gases/Gaseous objects|Gaseous objects}}
[[Image:Methane bubbles.jpe.jpeg|thumb|right|2
050px|Methane bubbles are trapped in lake ice in Siberia in early autumn. Credit: Katey Walter, AP/Nature.]]
"Methane trapped in a special type of permafrost [in the image at the right] is bubbling up at rate five times faster than originally measured [...]."<ref name=Borenstein>{{ cite book
|author=Seth Borenstein
|title=Scientists Find New Global Warming 'Time Bomb’
|publisher=Common Dreams News Center
|location=
|month=September 7,
|year=2007
|url=http://www.thewe.cc/weplanet/news/arctic/permafrost_melting.htm#this_is_real
|accessdate=2014-09-20 }}</ref>
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==Liquid objects==
{{main|Liquids/Liquid objects|Liquid objects}}
[[Image:Thermokarst lakes.jpe.jpeg|thumb|right|2050px|An aerial view shows thermokarst lakes in northeast Siberia. Credit: Dmitry Solovyov/REUTERS.]]
[[Image:ThermokarstGlossary.jpg|thumb|left|2050px|Increased thawing of frozen ground could create more thermokarst features, like this lake. Credit: Andrew Slater.]]
'''Def.''' "water that forms transition layers at mineral/water and mineral/water/ice interfaces in frozen ground"<ref name=Beitler/> is called '''interfacial water'''.

(contracted; show full)spheric deposition and groundwater seepage. Paul Lake generally remains stratified year-long because of a biogenic meromixis [...] and has been classified mesotrophic [...]. The concentration of soluble reactive phosphorus remains low in surface waters year-long, but nutrient regeneration at the oxic/anoxic transition promotes phyto-planktonic blooms just above this interface [...]."<ref name=Lienemann/>
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==Rocky objects==
{{main|Rocks/Rocky objects}}
[[Image:BlueRock.jpg|thumb|right|2
050px|This Sin-Kamen (''Blue Rock'') near Lake Pleshcheyevo used to be a Meryan shrine Credit: Viktorianec.]]
[[Image:Blue rock from Berkeley hills.jpg|thumb|left|2050px|This is a blue rock, probably various copper minerals, from the Berkeley hills near San Francisco, California. Credit: [[w:User:Looie496|Looie496]].]]
[[Image:Glacial erratic Canada.jpg|thumb|right|2050px|A sense of the size of the glacial erratic can be estimated by noting the person standing in front of the boulder, on the left side. Credit: Lynda Dredge, Natural Resources Canada, Terrain Sciences Division, Geological Survey of Canada.]]
[[Image:Glacial erratic.jpg|thumb|left|Glacial erratic (granite) is in the Polish Geological Institute, Warsaw. Credit: Robert Niedźwiedzki.]]
(contracted; show full)

"A sense of the size of the glacial erratic [imaged at the right in northeastern Manitoba, Canada]] can be estimated by noting the person standing in front of the boulder, on the left side. This erratic, as well as neighboring ones, were carried by the Keewatian Ice Sheet."<ref name=Beitler/>
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==Astrochemistry==
{{main|Astrochemistry}}
[[Image:Yedoma small.jpg|thumb|right|2
050px|A yedoma in Russia shows the thick layer of ice and carbon material exposed along a body of water. Credit: Vladimir Romanovsky.]]
'''Def.''' a "type of Pleistocene-age (formed 1.8 million to 10,000 years before present) permafrost that contains a significant amount of organic material with ice content of 50-–90% by volume"<ref name=Beitler/> is called '''yedoma'''.

In the image at the right, a yedoma in Russia is a thick layer of ice and carbon material exposed along this body of water. "Thawing yedoma is a significant source of atmospheric methane."<ref name=Beitler/>
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==Carbons==
{{main|Chemicals/Carbons|Carbons}}
[[Image:Yedoma carbon.jpe.jpeg|thumb|right|2050px|Here, carbon is trapped in permafrost. Credit: Katey Walter.]]
At the right is an image of yedoma.

"The shiny surface of the cliff represents massive ice wedges."<ref name=BorensteinAugust>{{ cite book
|author=Seth Borenstein
|title=Scientists Find New Global Warming 'Time Bomb’
|publisher=the We
|location=
(contracted; show full)
{{clear}}

==Aluminums==
{{main|Chemicals/Aluminums|Aluminums}}
[[Image:Andean glacial sites.jpg|thumb|center|400px|Sampling locations are in and along the upper 12 km of the Rio Quilcay, Cordillera Blanca, Peru. Main stream samples are labeled 1–24, tributaries A–F. Credit: Sarah K. Fortner, Bryan G. Mark, Jeffrey M. McKenzie, Jeffrey Bury, Annette Trierweiler, Michel Baraer, Patrick J. Burns, and LeeAnn Munk.]]
[[Image:Tributary C Andean glaciers.jpg|thumb|right|2
050px|Tributary C feeds the Northeast Branch of the Rio Quilcay, Peru. This tributary has abundant ochreous precipitates. Credit: Sarah K. Fortner, Bryan G. Mark, Jeffrey M. McKenzie, Jeffrey Bury, Annette Trierweiler, Michel Baraer, Patrick J. Burns, and LeeAnn Munk.]]
(contracted; show full)image at the right]. Evidence for this includes a major cation: SO<sub>4</sub><sup>2-</sup> equivalent ratio of 1, and abundant algal mats covered with yellow and orange precipitates (Bigham et al., 1996). In addition, dissolved Al and Zn increased an additional 270% and 160% relative to site 13–14, respectively, and after the inflow of tributary D."<ref name=Fortner/>
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==Cobalts==
{{main|Chemicals/Cobalts|Cobalts}}
[[Image:Paul Lake dissolved cobalt.jpg|thumb|2
050px|The distribution of the concentrations of dissolved cobalt (Co<sub>d</sub>) observed in May 1994 (filled circles) and July-August 1995 (shaded squares) are presented. Credit: Charles-Philippe Lienemann, Martial Taillepert, Didier Perret, and Jean-François Gaillard.]]
(contracted; show full)

In the oxic mixolimnion, dissolved Co remains primarily under its free hydrated form (Co[H<sub>2</sub>]<sup>2+</sup><sub>6</sub>, whereas in the anoxic bottom waters it seems to be primarily present as a sulfide complex (CoS<sup>0</sup>).
{{clear}}

==Coppers==
{{main|Chemicals/Coppers|Coppers}}
[[Image:Landsat Thematic Mapper Manitouwadge.jpg|thumb|right|2
050px|This is a Landsat Thematic Mapper image with overlain geological structures. Credit: I.M. Kettles, A.N. Rencz, and S.D. Bauke.]]
"Approximately five million tonnes were mined from native copper deposits in Michigan. Copper masses from the Michigan deposits were transported by the Pleistocene glaciers. Areas on the copper surfaces which appear to represent glacial abrasion show minimal corrosion."<ref name=Johnson1980>{{ cite journal
|author=A.B. Johnson Jr. and B. Francis
(contracted; show full)|doi=
|pmid=
|accessdate=2014-10-28 }}</ref>
{{clear}}

==Compounds==
{{main|Chemicals/Compounds|Compounds}}
[[Image:Artic-seabed-methane-gas-leakage.gif|thumb|right|2
050px|The diagram describes how methane leaks from sea beds. Credit: Katey Walter, University of Alaska at Fairbanks.]]
The diagram at the right describes how methane (CH<sub>4</sub>) leaks from sea beds.

"Methane is far more powerful in trapping heat, but only lasts about a decade before it dissipates into carbon dioxide and other chemicals. Carbon dioxide traps heat for about a century."<ref name=Borenstein/>
{{clear}}

==Meteorites==
{{main|Rocks/Meteorites|Meteorites}}
[[Image:Willamette Meteorite AMNH.jpg|thumb|left|150px|The Williamette Meteorite is on display at the American Museum of Natural History in New York City. Credit: [[w:User:Dante Alighieri|Dante Alighieri]].]]
[[Image:Widmanstatten patterns 2.jpg|thumb|right|2050px|This image is a cross-section of the Laguna Manantiales meteorite showing [[w:Widmanstätten pattern|Widmanstätten patterns]]. Credit: [[commons:User:Aramgutang|Aram Dulyan]].]]
[[Image:Avalanche by Armstrong.jpg|thumb|right|2050px|This shows an avalanche in motion. Credit: Richard Armstrong, National Snow and Ice Data Center.]]
[[Image:Avalanche.jpg|thumb|left|2050px|An avalanche is coming down the face of Mount Index, WA. Credit: [[commons:User:Josh Lewis|Josh Lewis]].]]
'''Def.''' "[a] [[wikt:metallic|metallic]] or [[wikt:stony|stony]] object that is the remains of a [[wikt:meteor|meteor]]", from Wiktionary [[wikt:meteorite|meteorite]], is called a '''meteorite'''.

Many of the meteorites that are found on [[Earth]] turn out to be from other solar system objects: the Moon and Mars, for example.

'''Widmanstätten patterns''', also called '''Thomson structures''', are unique figures of long [[w:nickel|nickel]]-[[w:iron|iron]] crystals, found in the [[w:octahedrite|octahedrite]] [[w:iron meteorite|iron meteorite]]s and some [[w:pallasite|pallasite]]s. They consist of a fine interleaving of [[w:kamacite|kamacite]] and [[w:taenite|taenite]] bands or ribbons called ''lamellæ''. Commonly, in gaps between the lamellæ, a fine-grained mixture of kamacite and taenite called [[w:plessite|plessite]] can be found.

'''Def.''' a "mass of snow which becomes detached and slides down a slope, often acquiring great bulk by fresh addition as it descends"<ref name=Beitler/> is called an '''avalanche'''.
{{clear}}

==Micrometeorites==
{{main|Rocks/Micrometeorites|Micrometeorites}}
[[Image:Micrometeorite.jpg|thumb|right|2050px|This is a micrometerorite collected from the antarctic snow. Credit: NASA.]]
Micrometeorite is often abbreviated as MM. Most MMs are broadly chondritic in composition, meaning "that major elemental abundance ratios are within about 50% of those observed in [[w:carbonaceous chondrite|carbonaceous chondrite]]s."<ref name=Taylor/> Some MMs are [[w:chondrite|chondrite]]s, (basaltic) [[w:HED meteorite|howardite, eucrite, and diogenite (HED) meteorite]]s or Martian basalts, but not lunar sampl(contracted; show full)|doi=10.1111/j.1945-5100.2007.tb00229.x
|pmid=
|accessdate=2011-08-07 }}</ref>
{{clear}}

==Atmospheric astronomy==
{{main|Astronomy/Atmospheres|Atmospheric astronomy}}
[[Image:Atmospheric Water Vapor Mean.2005.030.jpg|thumb|left|2
050px|This is a graph of the global mean atmospheric water vapor superimposed on an outline of the Earth. Credit: NASA.]]
[[Image:SG haze-skyline.JPG|thumb|right|2050px|This image demonstrates obstacles to observation (the Singapore skyline) and one atmospheric object: [[w:haze|haze]]. Credit: [[commons:User:SpLoT|SpLoT]].]]
(contracted; show full)* [[w:Mesosphere|Mesosphere]] &mdash; Stratosphere to 85 km
* [[w:Thermosphere|Thermosphere]] &mdash; Mesosphere to 675 km
* [[w:Exosphere|Exosphere]] &mdash; Thermosphere to 10,000 km, after [[w:Altitude#Altitude regions|altitude regions]].
{{clear}}

==Ionospheres==
{{main|Astronomy/Atmospheres/Ionospheres|Ionospheres}}
[[Image:Ionosphere-Thermosphere Processes.jpg|thumb|right|2
050px|In this diagram, the prominent features in the ionosphere-thermosphere system and their coupling to the different energy inputs show the complex temporal and spatial phenomena that are generated. Credit: NASA.]]
Upon reaching the top of the [[w:Mesosphere|mesosphere]], the temperature starts to rise, but air pressure continues to fall. This is the beginning of the [[w:ionosphere|ionosphere]], a region dominated by chemical ions. Many of them are the same chemicals such as [[w:nitrogen|nitrogen]] and [[w:oxygen|oxygen]] in the atmosphere below, but an ever increasing number are hydrogen ions ([[w:proton|proton]]s) and helium ions. These can be detected by an ion spectrometer. The process of [[w:ionization|ionization]] removes one or more [[w:electron|electron]]s from a neutral atom to yield a variety of ions depending on the chemical element species and incidence of sufficient energy to remove the electrons.
{{clear}}

==Exospheres==
{{main|Astronomy/Atmospheres/Exospheres|Exospheres}}
Into the exosphere or outer space, temperature rises from around 1,500°C to upwards of 100,000 K.

==Sun==
{{main|Stars/Sun|Sun (star)}}
[[Image:Sun rise in Kodachadri.JPG|thumb|right|2050px|The image shows a sunrise in Kodachadri. Credit: [[commons:User:Chinmayahd|Chinmayahd]].]]
[[Image:Orange Sun in Boracay, Philippines.jpg|thumb|left|2050px|The image shows an orange sun in Boracay, Philippines. Credit: [[commons:User:Sarahr|Sarahr]].]]
The Sun passes overhead every day on Earth. The size of its disc is very close to that of the Moon.

Regarding the fixed stars, the Sun appears from Earth to revolve once a year along the [[w:ecliptic|ecliptic]] through the zodiac, and so Greek astronomers considered it to be one of the seven [[w:planet|planet]]s (Greek ''planetes'', "wanderer"), after which the seven days of the [[w:week|week]] are named in some languages.<ref name=oed>{{ cite book
| url= http://dictionary.oed.com/cgi/entry/50180718?query_type=word&queryword=planet
|publisher = Oxford English Dictionary
| title = planet, n.
| accessdate=2008-02-07
|month=December
|year=2007 }} ''Note: select the Etymology tab ''</ref><ref name=Goldstein>{{ cite journal
|author=Bernard R. Goldstein
|title=Saving the phenomena : the background to Ptolemy's planetary theory
| journal=Journal for the History of Astronomy
|volume=28
|issue=1
|year=1997
|pages=1–12
|location=Cambridge (UK) 
|bibcode=1997JHA....28....1G⏎
|ref=harv }}</ref><ref name=Ptolemy>{{ cite book
|title=Ptolemy's Almagest
|author= Ptolemy|coauthors=Toomer, G. J.|publisher=Princeton University Press|year=1998|isbn=9780691002606}}</ref>

"And Helios, lord of the sun, sitting Away from the other gods, sitting in his own temple And listening to prayers breathing up from men: he heard."<ref name=Raffel>{{ cite journal
|author=Burton Raffel
|title=Homeric Hymn to Demeter 1-89
|journal=Arion
|month=Winter
|year=1970
|volume=9
|issue=4
|pages=415-20
|url=http://www.jstor.org/stable/10.2307/20163307
|arxiv=
|bibcode=
|doi=10.2307/20163307
|pmid=
|accessdate=2012-04-24 }}</ref>

"[A]stronomically, the visible Helios occupies the central position among the seven planets - Kronos, Zeus, Ares, Helios, Aphrodite, Hermes, and Selene, in a descending series."<ref name=Pack>{{ cite journal
|author=Roger Pack
|title=Notes on the Caesars of Julian
|journal=Transactions and Proceedings of the American Philological Association
|month=
|year=1946
|volume=77
|issue=
|pages=151-7
|url=http://www.jstor.org/stable/10.2307/283452
|arxiv=
|bibcode=
|doi=
|pmid=
|accessdate=2012-04-24 }}</ref>
{{clear}}

==Skies==
{{main|Astronomy/Skies|Sky astronomy}}
[[Image:Clouds over the Atlantic Ocean.jpg|thumb|right|2050px|Although the image contains a layer of cumulus clouds, at the horizon, the [[w:Atlantic Ocean|Atlantic Ocean]] meets the edge of the sky. Location :Salvador, Bahia, Brazil, July 4, 2008. Credit: [[commons:User:Tfioreze|Tiago Fioreze]].]]
Being outside in the day light to look upward when the Sun is off to the East or West, you may see that the [[w:Diffuse sky radiation|sky is blue]] depending on the [[w:weather|weather]].

(contracted; show full)'''Def.''' an "expanse of space that seems to be [overhead] like a dome"<ref name=Gove/> is called a '''sky'''.

Even in day light, the sky may seem absent of objects if a nearby source tends to overwhelm other luminous objects.
{{clear}}

==Volcanoes==
{{main|Volcanoes}}
[[Image:MountRedoubtEruption.jpg|thumb|left|2
050px|Mount Redoubt in Alaska erupted on April 21, 1990. The mushroom-shaped plume rose from avalanches of hot debris that cascaded down the north flank. Credit: R. Clucas, USGS.]]
[[Image:Ash and Steam Plume, Soufriere Hills Volcano, Montserrat.jpg|thumb|right|2050px|This oblique astronaut photograph from the International Space Station (ISS) captures a white-to-grey volcanic ash and steam plume extending westwards from the Soufriere Hills volcano. Credit: NASA Expedition 21 crew.]]
Oblique images such as the one at right are taken by astronauts looking out from the ISS at an angle, rather than looking straight downward toward the [[Earth]] (a perspective called a nadir view), as is common with most remotely sensed data from satellites. An oblique view gives the scene a more three-dimension quality, and provides a look at the vertical structure of the volcanic plume. While much of the island is covered in green vegetation, grey deposits that include pyroclastic flows and volcanic mud-flows (lahars) are visible extending from the volcano toward the coastline. When compared to its extent in earlier views, the volcanic debris has filled in more of the eastern coastline. Urban areas are visible in the northern and western portions of the island; they are recognizable by linear street patterns and the presence of bright building rooftops. The silver-grey appearance of the Caribbean Sea surface is due to sun-glint, which is the mirror-like reflection of sunlight off the water surface back towards the hand-held camera on-board the ISS. The sun-glint highlights surface wave patterns around the island.
{{clear}}

==Craters==
{{main|Astronomy/Craters|Crater astronomy}}
[[Image:Barringer Crater aerial photo by USGS.jpg|thumb|left|2050px|This is an aerial view of the Barringer Meteor Crater about 69 km east of Flagstaff, Arizona. Credit:D. Roddy, U.S. Geological Survey.]]
[[Image:Yucatan chix crater.jpg|thumb|right|120px|The Chicxulub impact crater is outlined. Credit: NASA/JPL-Caltech, modified by [[w:User:David Fuchs|David Fuchs]].]]
[[Image:USGS Decorah crater.jpg|thumb|right|2050px|U.S. Geological Survey aerial electromagnetic resistivity map of the Decorah crater has been produced. Credit: USGS.]]
Occasionally, objects fall from the sky. When and where this occurs, depending on the [[energy]] dumped into the atmosphere and the impact on the crust of the Earth, life forms nearby hear it, feel the vibrations from it, and recoil if the intensity is too high.

(contracted; show full)

"The shale is an ideal target and provides the electrical contrast that allows us to clearly image the geometry and internal structure of the crater," Bedrosian said.<ref name=Koontz/>
{{clear}}

==Tides==
{{main|Tidal astronomy|Astronomy/Tides}}
[[Image:Birds gathering on shoreline at low tide, Sandwich Bay - geograph.org.uk - 1002204.jpg|thumb|right|230px|Here at low tide in Sandwich Bay birds are gathering. Credit: Nick Smith.]]
[[Image:Fundy High & Low tide.jpg|thumb|left|2
050px|"This pair of images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite shows the dramatic difference in the amount of water-covered land at the head of the southeast corner of the bay during a high tide on April 20, 2001, and a low tide on September 30, 2002. Vegetation is green, and water ranges from dark blue (deeper water) to light purple (shallow water)."<ref name=Wiscombe>{{ cite book
|author=Warren Wiscombe
|title=High and Low Tides in Bay of Fundy
|publisher=NASA Earth Observatory
|location=NASA Goddard Space Flight Center
|month=June 14,
|year=2006
|url=http://earthobservatory.nasa.gov/IOTD/view.php?id=6650
|accessdate=2012-05-27 }}</ref> Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.]]
[[Image:A beach in Oban - geograph.org.uk - 14019.jpg|thumb|right|2050px|In Oban, U.K., the tide has gone out. Credit: Angelia Streluk.]]
In addition to the Sun, the Moon affects life forms on Earth such as those along the shores of bodies of water through the production of [[w:Tide|tide]]s.

"Due to phenomena such as ice ages, plate tectonics, land uplift, erosion and sedimentation, tides have changed dramatically over thousands of years"<ref name=Hill>{{ cite book
|author=David Hill
|title=Ancient Tides Different from Today - Some Dramatically Higher
(contracted; show full)

Today Hudson Bay is a place "where tidal energy gets dissipated at a disproportionately high rate ... But during the last ice age Hudson Bay was closed down and buried in ice, and that caused more extreme tides elsewhere."<ref name=Hill/>
{{clear}}

==Auroras==
{{main|Plasmas/Plasma objects/Auroras|Auroras}}
{{main|Earth/Auroras|Earth auroras}}
[[Image:Polarlicht.jpg|thumb|right|2
050px|The Aurora Borealis, or Northern Lights, shines above Bear Lake, Alaska. Credit: Senior Airman Joshua Strang, United States Air Force.]]
[[Image:Aurora borealis in a lab dsc04517.jpg|thumb|right|2050px|Laboratory experiment produces aurora at the poles of a sphere. Credit: [[commons:User:David Monniaux|David Monniaux]].]]
Computer simulations are usually used to represent auroras. The image at right shows a [[w:terrella|terrella]] in a laboratory experiment to produce auroras.

"Although auroras might first appear to be moonlit clouds, they only add light to the sky and do not block background stars from view. Called "Northern Lights" in the Northern Hemisphere, auroras are caused by collisions between charged particles from the magnetosphere and air molecules high in the Earth's atmosphere. If viewed from space, auroras can be seen to glow in X-ray and ultraviolet light as well. Predictable auroras might occur a few days after a powerful magnetic event has been seen on the sun."<ref name=Harvey11S>{{ cite book
|author=Samantha Harvey
|title=Aurora Over Norway
|publisher=NASA
|location=
|month=September 28,
|year=2011
|url=http://solarsystem.nasa.gov/multimedia/display.cfm?Category=GreatShots&IM_ID=12648
|accessdate=2012-07-21 }}</ref>

Most aurorae occur in a band known as the ''auroral zone'',<ref name="feldstein63">{{cite journal⏎
⏎
|year=1963⏎
⏎
|title=Some problems concerning the morphology of auroras and magnetic disturbances at high latitudes⏎
⏎
|journal= Geomagnetism and Aeronomy  ⏎
⏎
|volume=3⏎
⏎
|pages= 183–192⏎
⏎
|author=Feldstein, Y. I.  }}</ref><ref name="feldstein86">{{cite journal⏎
⏎
|bibcode=1986EOSTr..67..761F⏎
⏎
|author=Feldstein, Y. I.  ⏎
⏎
|year=1986⏎
⏎
|title= A Quarter Century with the Auroral Oval⏎
⏎
|journal= EOS⏎
⏎
|volume=67⏎
⏎
|issue= 40⏎
⏎
|page= 761⏎
⏎
|doi=10.1029/EO067i040p00761-02 }}</ref> which is typically 3° to 6° in latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole defined by the axis of the Earth's magnetic dipole. During a [[w:geomagnetic storm|geomagnetic storm]], the auroral zone will expand to lower latitudes. The diffuse aurora is a featureless glow in the sky which may not be visible to the naked eye even on a dark night and defines the extent of the auroral zo(contracted; show full)|doi=
|pmid=
|accessdate=2011-11-08 }}</ref>
{{clear}}

==Tephra layers==
{{main|Geochronology/Tephra layers|Tephra layers}}
[[Image:Ashfall from Pinatubo, 1991.jpg|thumb|right|2
050px|The volcanic eruption from Mount Pinatubo deposits a snowlike blanket of tephra on June 15, 1991. Credit: R.P. Hoblitt, USGS.]]
An ashfall occurs from a nearby volcano, before the locals can leave the area or maybe even go to work.
{{clear}}

==Foliation==
[[Image:Beach In Cornwall UK.jpg|thumb|right|2050px|The image shows finely layered slate perhaps with occasional dolomite layers exposed on a beach in Cornwall, UK. Credit: [[commons:User:Si Griffiths|Si Griffiths]].]]
[[Image:Meguma3.jpg|thumb|right|2050px|The image shows folds in slate and quartzite of the Meguma Group near the Ovens, Nova Scotia, Canada. Credit: [[commons:User:Rygel,_M.C.|Michael C. Rygel]].]]
'''Slate''' is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock.<ref name=Marshak>Essentials of Geology, 3rd Ed, Stephen Marshak</ref> Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression.<ref name=Marshak/> Slate is frequently grey in color, especially when seen, en masse, covering roofs. However, slate occurs in a variety of colors even from a single locality; for example, slate from North Wales can be found in many shades of grey, from pale to dark, and may also be purple, green or cyan.
{{clear}}

==Glaciology==
{{main|Rocks/Glaciers/Glaciology|Glaciology}}
[[Image:Taku glacier.jpg|thumb|left|2050px|Taku Glacier winds through the mountains of southeastern Alaska. Credit: U. S. Navy.]]
[[Image:Receding glacier-en.svg|2050px|thumb|right|The diagram illustrates the interrelationship of glaciology terms. Credit: .]]
[[Image:Icefield.jpg|thumb|2050px|left|This is an aerial image of the Kalstenius Icefield on Ellesmere Island, Canada. Credit: the Royal Canadian Air Force, archived at the World Data Center for Glaciology, Boulder, CO.]]
'''Def.''' "a mass of ice that originates on land, usually having an area larger than one tenth of a square kilometer"<ref name=Beitler/> is called a '''glacier'''.

(contracted; show full)

The image at the left of "Kalstenius Icefield, located on Ellesmere Island, Canada, shows vast stretches of ice. The icefield produces multiple outlet glaciers that flow into a larger valley glacier. The glacier in this photograph is three miles wide."<ref name=Beitler/>
{{clear}}

==Astroglaciology==
[[Image:Vatnajökull.jpeg|thumb|2
050px|Vatnajökull, [[Iceland]] has an ice cap. Credit: NASA.]]
The discoveries of water ice on the [[Draft:Moon]], [[Draft:Mars]] and [[Draft: Europa]] add an extraterrestrial component to the field, as in "astroglaciology".<ref name=Williams>{{ cite journal
|title=Annals of Glaciology
|volume=9
|page=255
|author=Richard S. Williams, Jr.
|url=http://www.igsoc.org/annals/9/igs_annals_vol09_year1987_pg254-255.pdf
|year=1987
|publisher=International Glaciological Society
|accessdate=7 February 2011}}</ref>
{{clear}}

==Glaciers==
{{main|Rocks/Glaciers|Glaciers}}
[[Image:Piedmont glacier.jpg|thumb|right|2050px|The massive lobe of Malaspina Glacier in Alaska is clearly visible in this photograph taken from a Space Shuttle flight. Credit: NASA.]]
[[Image:Branched valley glacier.jpg|thumb|right|2050px|In this photograph from 1969, small glaciers flow into the larger Columbia Glacier from mountain valleys on both sides. Credit: United States Geological Survey.]]
[[Image:Tidewater glacier Holgate.jpg|thumb|right|2050px|This shows the terminus of Holgate Glacier. Credit: Janet Beitler, National Snow and Ice Data Center.]]
'''Def.''' a "large ice lobe spread out over surrounding terrain, associated with the terminus of a large mountain valley glacier"<ref name=Beitler/> is called a '''piedmont glacier'''.

(contracted; show full)

'''Def.''' a "mountain glacier that terminates in the ocean"<ref name=Beitler/> is called a '''tidewater glacier'''.
{{clear}}

==Asteroids==
{{main|Rocks/Rocky objects/Asteroids|Asteroids}}
[[Image:2008VK184-year2014.png|thumb|right|2
050px|The close approach of apollo asteroid 2007 VK184 was in May 2014. Credit: Osamu Ajiki (AstroArts) and Ron Baalke (JPL).]]
[[Image:2007vk184a.jpg|thumb|right|2050px|Asteroid 2007 VK184 has been eliminated as Impact Risk to Earth. Credit: Steven Chesley.]]
[[Image:2012 LZ1.jpg|thumb|right|2050px|This image is of asteroid 2012 LZ1 by the Arecibo Observatory in Puerto Rico using the Arecibo Planetary Radar. Credit: Arecibo Observatory.]]
"From the dominant group, the asteroids evolve to intersect the Earth's orbit on a median time scale of about 60 Myr."<ref name=Michel>{{ cite journal
|author=Patrick Michel, Fabbio Migliorini, Alessandro Morbidelli, Vincenzo Zappalà
|title=The Population of Mars-Crossers: Classification and Dynamical Evolution
|journal=Icarus
|month=June
(contracted; show full)|year=2012
|url=http://news.discovery.com/space/asteroid-2012-lz1-just-got-supersized-120622.htm
|accessdate=2013-10-24 }}</ref>
{{clear}}

==Recent history==
{{main|History/Recent|Recent history}}
[[Image:Bergschrund.jpg|thumb|right|2
050px|The image from 1936 shows explorers on Skillet Glacier. Credit: Janet Beitler.]]
The '''recent history''' period dates from around 1,000 b2k to present.

'''Def.''' a "crevasse that separates flowing ice from stagnant ice at the head of a glacier"<ref name=Beitler/> is called '''bergschrund'''.

(contracted; show full)

Sedimentary rocks cover most of the [[Earth]]'s surface, record much of the Earth's history, and harbor the fossil record. Sedimentology is closely linked to stratigraphy, the study of the physical and temporal relationships between rock layers or strata.
{{clear}}

==Triassic==
{{main|History/Triassic|Triassic}}
[[Image:Triassic Utah.JPG|thumb|right|2
050px|This middle Triassic marginal marine sequence in southwestern Utah consists of siltstones and sandstones. Credit: [[w:User:Wilson44691|Wilson44691]].]]
The '''Triassic'''/Jurassic boundary occurs at 205.7 ± 4.0 Ma (million years ago).<ref name=Gradstein>{{ cite journal
|author=Felix M. Gradstein, Frits P. Agterberg, James G. Ogg, Jan Hardenbol, Paul Van Veen, Jacques Thierry, and Zehui Huang
|title=A Triassic, Jurassic and Cretaceous Time Scale, In: ''Geochronology Time Scales and Global Stratigraphic Correlation''
|volume=SEPM Special Publication No. 54
|publisher=Society for Sedimentary Geology
|location=
|month=
|year=1995
|editor=
|volume=⏎
|issue=
|pages=
|url=http://archives.datapages.com/data/sepm_sp/SP54/A_Triassic_Jurassic_and_Cretaceous_Time_Scale.htm
|arxiv=
|bibcode=
|doi=1-56576-024-7
|pmid=
|isbn=
|accessdate=2017-02-09 }}</ref>

The Permian/'''Triassic''' boundary occurs at 248.2 ± 4.8 Ma (million years ago).<ref name=Gradstein/>
{{clear}}

==Structural geology==
{{main|Earth/Geology/Structures|Structural geology}}
[[Image:Quebrada de Cafayate, Salta (Argentina).jpg|thumb|right|2050px|The image shows rock strata in Cafayate, Argentina. Credit: travelwayoflife.]]
[[Image:BarstowFormationAnticlineMarch2010.jpg|thumb|right|2050px|The image shows an anticline in the Barstow Formation (Miocene) at Calico Ghost Town near Barstow, California USA. Credit: [[commons:User:Wilson44691|Wilson44691]].]]
The image at the right shows rock strata in Cafayate, Argentina, the subject of [[stratigraphy]].

'''Structural geology''' is the study of the three-dimensional distribution of rock units with respect to their deformational histories.
{{clear}}

==Technology==
{{main|Technology}}
[[Image:Methane measurements siberia.jpe.jpeg|thumb|right|2050px|An under water, under ice bubble trap is installed on a lake in Siberia. Credit: Katey Walter.]]
Here at the right an under water, under-ice bubble trap is installed in a lake in Siberia.
{{clear}}

==Aircraft==
{{main|Astronomy/Airborne|Airborne astronomy}}
[[Image:446826main ED10-0080-03c 946-710.jpg|thumb|right|2050px|The SOFIA observatory is flying with 100% open telescope door. Credit: NASA.]]
The "Stratospheric Observatory for Infrared Astronomy [(SOFIA) is] mounted onboard a Boeing 747SP. [...] SOFIA’s 2.7 m mirror and optimized telescope system combines the highest available spatial resolution with excellent sensitivity. SOFIA will operate in both celestial hemispheres for the next two decades."<ref name=Krabbe>{{ cite book
| author=Alfred Krabbe
| title=SOFIA telescope, In: ‘’Proceedings of SPIE: Astronomical Telescopes and Instrumentation’’
| pages=276–281
| date=March, 2007
| publisher=SPIE — The International Society for Optical Engineering
| location=Munich, Germany
|url=http://arxiv.org/pdf/astro-ph/0004253v1.pdf
| arxiv=astro-ph/0004253 }}</ref>

It has an operating altitude of 12-14 km, 39,000-45,000 ft and a spatial resolution of 1-3" for 0.3 < λ < 15 µm, and λ/10" for λ > 15 µm.<ref name=Krabbe/> 
{{clear}}

==Hypotheses==
{{main|Hypotheses}}
# Earth is a rocky object throughout most of its interior and exterior.⏎
{{seealso|Control groups|Proof of concept|Proof of technology}}

==See also==
{{div col|colwidth=12em}}
* [[Solar System, technical/Earth]]
{{Div col end}}

==References==
{{reflist|2}}

==External links==

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