Australites are tektites found in Australia. They are mostly dark or black, and have shapes including discs and bowls that are not seen in other tektites. NASA used the shape of "flanged button" australites in designing re-entry modules for the Apollo program in the 1960s.[1]
Aerodynamically shaped australite; the button shape is caused by ablation of molten glass in the atmosphere during reentry.
Indigenous Australians termed australites ooga ("staring eyes"), and they were used as sacred objects or as cutting tools.[2] Europeans found out about australites in 1857, when explorer Thomas Mitchell gave naturalist Charles Darwin a mysteriously shaped piece of natural black glass. Darwin thought that australites were of volcanic origin due to their similarity to obsidian, volcanic glass.[1][2][3] Later, australites were called blackfellows' buttons and obsidian bombs.[citation needed]
One of the first scientists to seriously study australites was Charles Fenner, who saw his first australite in 1907. He believed that australites were glass meteorites.[4]
Originedit
3 grams 'core-type' aerodynamically shaped Australite, looking like a miniature Apollo capsule.
Early theories about the source of australites included volcanoes, the bushfires that are common in Australia, or fusion of sand by lightning (fulgurites). Some scientists believed them to be meteorites, possibly lunar meteorites ejected from the Moon in impacts (now disproved due to the different composition of lunar rocks).[1]
Although different theories about the origin of australites are still circulating, most scientists believe that australites formed during a large asteroid or comet impact on the Earth. The impact ejected myriad small rocks right out of the atmosphere. The australites acquired their streamlined, aerodynamic forms when they re-entered the Earth's atmosphere while molten and travelling at high velocities.[1]
Most australites are found in Southern Australia, below 25 degrees latitude.[5] Based on similar ages[6] and compositions,[7] they represent the southern edge of the vast Australasian tektite strewnfield that stretches from southern China to Australia. The Australasian strewnfield has an age of 610,000 to 750,000 years and may be the result of an impact in Indochina.[5]
Shapesedit
A very rare shape of australite tektite - "shallow bowl"
The primary forms of australites are sphere, oval, boat, dumbbell and teardrop. Australites are smaller than other tektites and different in shape. Their initial velocity was higher than other tektites: enough to propel them just out of the Earth's atmosphere, so they then re-entered the atmosphere and underwent a rare secondary melting.[8]
One of the most famous australite shapes is the "flanged button". Flanged buttons are rare, but the most unusual and rarest australites are discs, bowls, plates and other small forms (mini tektites). They are very thin. George Baker called them "flying flanges", the result of distortion of "initially small primary forms by aerodynamic frictional heating". He wrote:
These are all very special forms of tektites not encountered among the other known tektite-strewn fields of the world, the rarity and unexcelled character of these well-preserved, complete to nearly complete, unique types of tektites cannot be overstressed.[9]
Chapman and Larson experimented on the ablation of australites. At first they seemed to prove their extraterrestrial origin, but later in repeated studies they claimed that the australites could not have come from outside the Earth-Moon system. They were able to reproduce the shapes, flanges and the peculiar network of the rings on the front face in great detail.[10]
^ abcd. Museum Victoria. Archived from the original on July 26, 2008. Retrieved 2010-04-28.
^ abCassidy, W. A. (1956). "Australite Investigations and their Bearing on the Tektite Problem". Meteoritics. 1 (4). Journal: Meteoritics, volume 1, number 4: 426. Bibcode:1956Metic...1..426C. doi:10.1111/j.1945-5100.1956.tb01378.x. Retrieved 2010-04-28.
^H. E. Landsberg (1965). Advances in Geophysics, Volume 10. ISBN9780120188116. Retrieved 2010-04-28.
April 07, 2024
australite, tektites, found, australia, they, mostly, dark, black, have, shapes, including, discs, bowls, that, seen, other, tektites, nasa, used, shape, flanged, button, australites, designing, entry, modules, apollo, program, 1960s, aerodynamically, shaped, . Australites are tektites found in Australia They are mostly dark or black and have shapes including discs and bowls that are not seen in other tektites NASA used the shape of flanged button australites in designing re entry modules for the Apollo program in the 1960s 1 Aerodynamically shaped australite the button shape is caused by ablation of molten glass in the atmosphere during reentry Contents 1 History 2 Origin 3 Shapes 4 See also 5 ReferencesHistory editIndigenous Australians termed australites ooga staring eyes and they were used as sacred objects or as cutting tools 2 Europeans found out about australites in 1857 when explorer Thomas Mitchell gave naturalist Charles Darwin a mysteriously shaped piece of natural black glass Darwin thought that australites were of volcanic origin due to their similarity to obsidian volcanic glass 1 2 3 Later australites were called blackfellows buttons and obsidian bombs citation needed One of the first scientists to seriously study australites was Charles Fenner who saw his first australite in 1907 He believed that australites were glass meteorites 4 Origin edit nbsp 3 grams core type aerodynamically shaped Australite looking like a miniature Apollo capsule Early theories about the source of australites included volcanoes the bushfires that are common in Australia or fusion of sand by lightning fulgurites Some scientists believed them to be meteorites possibly lunar meteorites ejected from the Moon in impacts now disproved due to the different composition of lunar rocks 1 Although different theories about the origin of australites are still circulating most scientists believe that australites formed during a large asteroid or comet impact on the Earth The impact ejected myriad small rocks right out of the atmosphere The australites acquired their streamlined aerodynamic forms when they re entered the Earth s atmosphere while molten and travelling at high velocities 1 Most australites are found in Southern Australia below 25 degrees latitude 5 Based on similar ages 6 and compositions 7 they represent the southern edge of the vast Australasian tektite strewnfield that stretches from southern China to Australia The Australasian strewnfield has an age of 610 000 to 750 000 years and may be the result of an impact in Indochina 5 Shapes edit nbsp A very rare shape of australite tektite shallow bowl The primary forms of australites are sphere oval boat dumbbell and teardrop Australites are smaller than other tektites and different in shape Their initial velocity was higher than other tektites enough to propel them just out of the Earth s atmosphere so they then re entered the atmosphere and underwent a rare secondary melting 8 One of the most famous australite shapes is the flanged button Flanged buttons are rare but the most unusual and rarest australites are discs bowls plates and other small forms mini tektites They are very thin George Baker called them flying flanges the result of distortion of initially small primary forms by aerodynamic frictional heating He wrote These are all very special forms of tektites not encountered among the other known tektite strewn fields of the world the rarity and unexcelled character of these well preserved complete to nearly complete unique types of tektites cannot be overstressed 9 Well preserved shapes are found near Port Campbell in western Victoria Chapman and Larson experimented on the ablation of australites At first they seemed to prove their extraterrestrial origin but later in repeated studies they claimed that the australites could not have come from outside the Earth Moon system They were able to reproduce the shapes flanges and the peculiar network of the rings on the front face in great detail 10 See also editDarwin glassReferences edit a b c d Australites Museum Victoria Archived from the original on July 26 2008 Retrieved 2010 04 28 a b Cassidy W A 1956 Australite Investigations and their Bearing on the Tektite Problem Meteoritics 1 4 Journal Meteoritics volume 1 number 4 426 Bibcode 1956Metic 1 426C doi 10 1111 j 1945 5100 1956 tb01378 x Retrieved 2010 04 28 Australites Retrieved 2010 04 28 Australites a unique shower of glass meteorites by Charles Fenner 1934 Retrieved 2010 04 28 a b Tektites 2009 12 24 Archived from the original on 30 April 2010 Retrieved 2010 04 28 1 G A Izett J D Obradovich LPSC 33 1992 593 594 Blum et al Geochimica et Cosmochimica Acta 56 1992 83 492 Australite Shapes Jan 2010 Archived from the original on 2010 12 27 Retrieved 2010 04 28 Baker G 1963 Disc Plate and Bowl Shaped Australites Meteoritics 2 1 Meteoritics volume 2 number 1 36 Bibcode 1963Metic 2 36B doi 10 1111 j 1945 5100 1963 tb01402 x Retrieved 2010 04 28 H E Landsberg 1965 Advances in Geophysics Volume 10 ISBN 9780120188116 Retrieved 2010 04 28 Retrieved from https en wikipedia org w index php title Australite amp oldid 1170137527, wikipedia, wiki, book, books, library,
