Asteroid Impact Craters on Earth as Seen From Space

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Asteroid impact craters are among the most interesting geological structures on any planet. Many other
* H* D9 B2 i, \' ?- R$ H8 M7 V4 tplanets and moons in our solar system, including our own moon, are pock-marked with loads of craters. 5.39.217.77:8898  z) ^0 \" r+ ~
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic & Z# F. j. ?$ [
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
" |3 n( \$ @8 \. P& k, n3 e% gstructures don’t last long and can be tough to come by.TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。4 t9 d- ?* t2 b
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
8 t/ R( Q2 y; w6 @& d) e- ~One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here
( `% _. \+ `" ?tvb now,tvbnow,bttvbshow some of the biggest, oldest and most interesting impact craters on the planet.tvb now,tvbnow,bttvb7 w# t: r7 @" g/ q  X
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 5.39.217.77:8898& T( w0 O. C! @9 x  t) i% S% ]& ?
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million 0 u. n  j! r9 ~/ z: _
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent 公仔箱論壇/ X9 {$ Z0 _: o6 n- n0 m, K7 p2 \
unidirectional wind. The image above was taken by astronauts in the International Space Station in July. 5.39.217.77:88986 r3 u4 N# N8 e! ^  p2 m
In the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。* k8 n# p7 e1 K" j  U5 n
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The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
7 q2 _, M$ H/ [# Y; Hgeologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
2 \+ S, R+ R: H; a9 o5.39.217.77:8898could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
2 F7 u& A/ T. @# o0 o/ u公仔箱論壇seasonal salt-water lakes. This image was taken by the Landsat 7 satellite." @- M( K- p. P) N3 T
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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
" r' u- {% v9 i3 f% ]around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around
5 Q% Z1 a$ s  N/ s60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
) M* w. a4 W. ^  ^6 r/ c/ Uimpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
reservoir and popular salmon fishing location.( V/ I. O; G& H4 J. e
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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
/ C+ D% [' O, [4 h公仔箱論壇an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
% A0 t6 X" q) U, H" vthe weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
) b6 j6 q8 w; I8 @and 900 million years old and the raised area at its center is around 1,600 feet wide.* h& |. ?3 u/ s9 N5 X2 p' V

, W* O% k0 F2 o, D  n- E; M, UThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on 1 E+ [: y! G4 @& o# E- |2 W# q
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite

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The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
+ c/ I( t6 ?2 V$ L5.39.217.77:8898center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding 4 O; k2 ^& C: k  r; ~" n! O4 v
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.$ a5 J0 Z, _* ?# W

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- Y( a# M1 ~# @7 c: O% E公仔箱論壇Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred tvb now,tvbnow,bttvb- ?6 L1 S. r' ^& u# Z$ |
simultaneously around 290 million years ago. The larger crater measures 22 miles across.5.39.217.77:8898  U, o3 }$ A( }1 E* `% |+ i
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The Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s
2 t/ q& b9 |  n7 n& i1.5 mile-wide rim stands out as a bright ring in the lower left of the image, which was taken by a radar instrument on board4 N5 E$ Z; g4 p* v  }9 _
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the tvb now,tvbnow,bttvb2 k2 {7 r6 M, X
photo is a rocky hill, the darkest areas are wind-blown sand dunes, the blue around the crater’s rim may be material that was 9 L3 `5 K( e. N' B, Q. @
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred 5.39.217.77:8898, Q4 l5 J- M( h" w  h( Y, x3 ?6 H! I
around 5 million years ago.TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。2 v' ]4 G  N8 F

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- x* R6 K4 i0 `5.39.217.77:8898The Lonar crater in Maharashta, India is around 6,000 feet wide and 500 feet deep and contains a saltwater lake.
/ P- b; p2 L5 u( Ztvb now,tvbnow,bttvbScientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
+ X4 ?' B3 T. ]. B8 _* ca glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. , U' }4 c5 H+ y9 d/ _
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
" J1 _2 N9 P0 a% a/ U2 x8 eTerra satellite. It is a simulated true-color image
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The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth. tvb now,tvbnow,bttvb+ f6 k9 K/ r3 X5 ]' ?% G  a/ U
The 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.
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Artist’s rendering of a space object or phenomenon, so we couldn’t resist this beauty. This is one man’s idea of what TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。. \- a1 X! }7 x' }# ^
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
Fortunately, NASA says nothing this big is headed our way anytime soon.