Hoba meteorite: Difference between revisions
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{{Infobox meteorite |
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|Name= Hoba |
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|Image= Hoba Meteorite sire.jpg |
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|Image_caption= The meteorite in 2013. |
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|Type= Iron |
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|Class= |
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|Group= [[IVB meteorites|IVB]] |
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|Structural_classification= [[Ataxite]] |
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|Composition= 84% [[Iron|Fe]], 16% [[Nickel|Ni]] |
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|Shock= |
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|Weathering= |
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|Country= [[Namibia]] |
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|Region= [[Grootfontein]], [[Otjozondjupa Region]] |
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|Lat_Long= {{coord|19|35|32.9|S|17|56|1.2|E|display=inline,title}}<ref name=database>{{metbull|11890|Hoba}}</ref> |
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|Observed_fall= No |
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|Fall_date= < 80,000 years ago |
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|Found_date= 1920 |
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|TKW= it weighs upto 60 tonnes[not exactly] |
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|Image2= Hoba_Meteorite_vandalism.jpg |
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|Image2_caption= Damage caused by sampling or vandalism |
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}} |
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'''Hoba'''<ref name=database /> (also known as '''Hoba West''') (pron. "HOE-bah") is a [[meteorite]] that lies on the farm "Hoba West", not far from [[Grootfontein]], in the [[Otjozondjupa Region]] of [[Namibia]]. It has been uncovered but, because of its large mass, has never been moved from where it fell. The main mass is estimated at more than 60 tons,<ref name=database/> making it the largest known [[meteorite]] (as a single piece) and the most massive naturally occurring piece of [[iron]] known at the Earth's surface. |
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==The fall== |
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The Hoba meteorite is thought to have fallen more recently than 80,000 years ago. It is inferred that the [[Earth's atmosphere]] slowed the object to the point that it fell to the surface at [[terminal velocity]], thereby remaining intact and causing little excavation. Assuming a drag coefficient of about 1.3, the meteor would have been slowed to a mere {{convert|320|m/s}} (contrast this with typical [[orbital speed]]s of several km/s). The meteorite is unusual in that it is flat on both major surfaces, possibly causing it to have skipped across the top of the atmosphere in the way a flat stone [[stone skipping|skips]] on water. |
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==Discovery== |
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[[File:Hoba Meteorite.jpg|thumb|left|200px|The Hoba meteorite before the construction of the circular steps.]] |
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The Hoba meteorite left no preserved [[Impact crater|crater]] and its discovery was a chance event. The owner of the land, Jacobus Hermanus Brits, encountered the object while ploughing one of his fields with an [[cattle|ox]]. During this task, he heard a loud metallic scratching sound and the plough came to an abrupt halt. The obstruction was excavated, identified as a meteorite and described by Mr. Brits, whose report was published in 1920 and can be viewed at the [[Grootfontein]] Museum in Namibia. |
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[[Friedrich Wilhelm Kegel]] took the first published photograph of the Hoba meteorite.<ref>{{Cite journal |title=Hoba (South-West Africa), the largest known meteorite |author=L.J. Spencer |coauthor=M.H. Hey |journal=The Mineralogical Magazine and Journal of the Mineralogic Society |url=http://giantcrystals.strahlen.org/library/hoba.pdf |number=136 |month=March |year=1932 |volume=XXIII <!-- 23 -->}} See page 4.</ref> |
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==Description and composition== |
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Hoba is a tabloid body of metal, measuring {{convert/3|2.7|x|2.7|x|0.9|m}}. In 1920 its mass was estimated at 66 tons. Erosion, scientific sampling and vandalism have reduced its bulk over the years. The remaining mass is currently estimated at just over 60 tons. The meteorite is composed of about 84% iron and 16% [[nickel]], with traces of [[cobalt]]. It is classified as an [[ataxite]] [[iron meteorite]] belonging to the nickel-rich chemical class [[IVB meteorites|IVB]]. A crust of iron [[hydroxide]]s is locally present on the surface, owing to weathering. |
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==Modern history== |
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In an attempt to control vandalism and with permission from Mrs. O. Scheel, owner of the farm at the time, the government of Namibia (then [[South West Africa]]) on March 15, 1955, declared the Hoba meteorite to be a National Monument.<ref>''Geochimica et Cosmochimica Acta'' 31, Geochemical Society. Pergamon Press, 1967. [http://books.google.it/books?id=TuoDAAAAMAAJ&q=%23Mrs.+RW+Scheel%23&dq=%23Mrs.+RW+Scheel%23&pgis=1 page 1470]</ref> |
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In 1985 [[Rössing]] Uranium Ltd. made resources and funds available to the Namibian government to provide additional protection against vandalism. In 1987 Mr. J. Engelbrecht, the owner of Hoba West farm, donated the meteorite and the site where it lies to the state for educational purposes. Later that year the government opened a tourist centre at the site. As a result of these developments, vandalism of the Hoba meteorite has ceased and it is now visited by thousands of tourists every year. |
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==See also== |
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* [[Glossary of meteoritics]] |
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==Notes and references== |
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{{Reflist}} |
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==Further reading== |
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*''[[Universe (book)|Universe: The Definitive Visual Dictionary]]'', Robert Dinwiddie, DK Adult Publishing, (2005), pg. 223. |
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*P.E. Spargo, "The History of the Hoba Meteorite Part I: Nature and Discovery," ''Monthly Notes of the Astronomical Society of Southern Africa'' 67, nos. 5/6 (2008), pp. 85–94. |
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*P.E. Spargo, "The History of the Hoba Meteorite Part II: The News Spreads," ''Monthly Notes of the Astronomical Society of Southern Africa'' 67, nos. 9/10 (2008), pp. 166–77. |
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*P.E. Spargo, "The History of the Hoba Meteorite Part III: Known and Loved by All," ''Monthly Notes of the Astronomical Society of Southern Africa'' 67, no. 12 (2008). [http://www.thefreelibrary.com/The+history+of+the+Hoba+Meteorite+III%3a+known+and+loved+by+all+...-a0199589514 Full text at The Free Library] |
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==External links== |
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{{Commons category|Hoba meteorite}} |
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{{Meteorites}} |
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{{Meteorites by name}} |
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{{DEFAULTSORT:Hoba Meteorite}} |
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[[Category:Meteorites found in Namibia]] |
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[[Category:Otjozondjupa Region]] |
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[[Category:Geography of Namibia]] |
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[[Category:Geology of Namibia]] |
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[[Category:National Monuments of Namibia]] |
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