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; h& R; t) b" `' ^6 @. I4 tAsteroid impact craters are among the most interesting geological structures on any planet. Many other
" r# I% f0 H. }  Ytvboxnow.complanets and moons in our solar system, including our own moon, are pock-marked with loads of craters. ' y; I+ r5 n" O- c& B4 N
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic tvboxnow.com2 |( P: X. Q* p3 d+ k
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
; B# ?/ J& H; D/ v2 Wstructures don’t last long and can be tough to come by.
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9 Z5 ?' E1 k2 {But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. * n) N* a2 v$ u6 U" j9 S
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here 公仔箱論壇  `+ Z, Y9 d# x4 Q1 d1 E
show some of the biggest, oldest and most interesting impact craters on the planet.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。  p& d# q6 A3 e) g" M, T
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks tvb now,tvbnow,bttvb2 W2 ~( Y+ |4 b
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
1 J# F2 R* N, eTVBNOW 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。years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent ) l3 G* B6 {( s" z4 M) z
unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
) F7 _" \% D9 r' x# r3 QIn the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.公仔箱論壇7 i& x! e4 t5 c! ]4 @( j8 O

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# e/ a7 Q% @- m- P& v8 }5 u公仔箱論壇The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 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 I$ ~+ K% V/ b2 I  Z2 A
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
. s# U: r" z( L, qcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are tvb now,tvbnow,bttvb9 f% p1 i- A+ J, l& K
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.tvboxnow.com% k( b* }" }, `+ e2 p) }! \/ k3 f
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9 J( `5 U3 D9 }+ c, {  GTVBNOW 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。公仔箱論壇. `' [7 z  V$ ]9 k2 I/ d& l
The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred 公仔箱論壇! N1 n: K: ~9 w/ f# i$ O
around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around 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。/ N6 f. \. x$ b- B7 X- A) C+ K* Q2 F3 e
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
- y4 Q8 m' t; o$ t5 r: qimpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a 公仔箱論壇5 r5 G& e; N  a
reservoir and popular salmon fishing location.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。+ P7 U' I9 h& I

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/ @; B) ^- d4 w! v! ]公仔箱論壇This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was 8 t- W! M$ C0 _( \! g  j
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
. m5 ?1 M" u' t0 {- l5 Q4 xtvb now,tvbnow,bttvblooking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
  M: ?3 T+ {. M7 Vthe weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
6 A8 P5 E% g( t2 X9 {! Z公仔箱論壇and 900 million years old and the raised area at its center is around 1,600 feet wide.1 G# q6 v- V- W+ }9 L) h
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The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
5 O# h9 l* L* C0 zNASA’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 tvb now,tvbnow,bttvb- b3 t5 R# v; l& i5 \' R3 s
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
" W5 n2 {+ k6 f: q" Xgrayish area. The crater was formed caused by an asteroid impact around 140 million years ago.
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Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred 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 C; R  s2 M" r" e( s
simultaneously around 290 million years ago. The larger crater measures 22 miles across.
2 x2 S, R3 ^' _$ `8 Y0 C! v5 B公仔箱論壇$ b, N5 Z/ `6 E# Q1 I1 x

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$ G1 E, s9 P; I( I' S; q: mtvb now,tvbnow,bttvbThe Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s 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。/ h/ v6 r2 b  ]3 F
1.5 mile-wide rim stands out as a bright ring in the lower left of the image, which was taken by a radar instrument on board公仔箱論壇( R0 `; R' B) H) ]( l9 A6 n* e
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
/ c* z; g- E& d# `tvb now,tvbnow,bttvbphoto is a rocky hill, the darkest areas are wind-blown sand dunes, the blue around the crater’s rim may be material that was
1 S  ~# L# s( Y! |) t$ qejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
. [* e9 A" Q" S1 w" |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。around 5 million years ago.
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The Lonar crater in Maharashta, India is around 6,000 feet wide and 500 feet deep and contains a saltwater lake.
; h1 C; P# b+ u. j2 Atvboxnow.comScientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, tvboxnow.com; f4 o! @. L9 U- ?- k$ `
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
+ [: T9 m0 b% L* }- ]# R2 Htvboxnow.comThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s 9 H, u# \1 `3 x: S6 c9 ?
Terra satellite. It is a simulated true-color imageTVBNOW 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。0 p4 a) F; l' v: i6 |$ w
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The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
9 _/ v5 Y  n/ G" E. Ntvboxnow.comThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.- m* {/ r( y- ?9 W. V: C
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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 tvboxnow.com; x( U# K3 y4 A
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
5 F6 B, Q! [  L0 k4 Xtvb now,tvbnow,bttvbFortunately, NASA says nothing this big is headed our way anytime soon.