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Keynote lectures/Earth
[[Image:Ice cap.jpg|thumb|right|250px|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|Keynote lectures/Astronomy}}
[[Image:Greenland 42.74746W 71.57394N.jpg|thumb|right|250px|Satellite composite image shows the ice sheet of Greenland. Credit: NASA.]]
(contracted; show full)may not be visible to the naked eye even on a dark night and defines the extent of the auroral zone. The discrete aurora are sharply defined features within the diffuse aurora which vary in brightness from just barely visible to the naked eye to bright enough to read a newspaper at night. Discrete aurorae are usually observed only in the [[w:night sky|night sky]] because they are as bright as the sunlit sky. Aurorae occasionally occur poleward of the auroral zone as diffuse patches<ref>{{cite journal
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|author=E. J. Weber⏎
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|year=1984⏎
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|title=F layer ionization patches in the polar cap⏎
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|doi=10.1029/JA089iA03p01683⏎
⏎
|journal= J. Geophys. Res.⏎
⏎
|volume= 89⏎
⏎
|issue= A3⏎
⏎
|pages= 1683–94⏎
⏎
|bibcode=1984JGR....89.1683W⏎
⏎
|author-separator=,⏎
⏎
|display-authors=1⏎
⏎
|last2=Buchau⏎
⏎
|first2=J.⏎
⏎
|last3=Moore⏎
⏎
|first3=J. G.⏎
⏎
|last4=Sharber⏎
⏎
|first4=J. R.⏎
⏎
|last5=Livingston⏎
⏎
|first5=R. C.⏎
⏎
|last6=Winningham⏎
⏎
|first6=J. D.⏎
⏎
|last7=Reinisch⏎
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|first7=B. W.⏎
⏎
}}</ref> or arcs (polar cap arcs<ref>{{ cite journal⏎
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|author=Frank⏎
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|year=1986⏎
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|title= The theta aurora⏎
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|journal= J. Geophys. Res.⏎
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|volume= 91⏎
⏎
|issue= A3⏎
⏎
|pages= 3177–3224⏎
⏎
|doi=10.1029/JA091iA03p03177⏎
⏎
|author-separator=,⏎
⏎
|author2=L. A.⏎
⏎
|display-authors=2⏎
⏎
|last3=Gurnett⏎
⏎
|first3=D. A.⏎
⏎
|last4=Shawhan⏎
⏎
|first4=S. D.⏎
⏎
|last5=Weimer⏎
⏎
|first5=D. R.⏎
⏎
|last6=Burch⏎
⏎
|first6=J. L.⏎
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|last7=Winningham⏎
⏎
|first7=J. D.⏎
⏎
|last8=Chappell⏎
⏎
|first8=C. R.⏎
⏎
|last9=Waite⏎
⏎
|first9=J. H.⏎
⏎
|bibcode=1986JGR....91.3177F⏎
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}}</ref>), which are generally invisible to the naked eye.
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==Natural electric fields==
{{main|Charges/Interactions/Electromagnetics/Electric fields/Earth|Natural electric field of the Earth}}
[[Image:-D3- LighningStormPanorama.jpg|thumb|right|300px|This is a panorama photograph taken during a lightning storm over Bucharest, Romania. Credit: [[w:User:Catalin.Fatu|Catalin.Fatu]].]]
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{{Radiation astronomy resources}}{{Sisterlinks|Earth}}

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