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3 d% V3 E$ L; ]& QTVBNOW 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。Asteroid impact craters are among the most interesting geological structures on any planet. Many other - G( u/ }8 J2 S% C4 |& x
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters. 1 V/ J! |* Y9 ~9 w/ H& a
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic 公仔箱論壇( g+ l$ G$ c2 E. E# i
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. tvboxnow.com- P/ ?; @2 ~* x, i/ r; _, k
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here tvb now,tvbnow,bttvb7 K- @+ \: k: v# c; F: ^
show some of the biggest, oldest and most interesting impact craters on the planet.tvboxnow.com$ L6 F4 n/ T5 @0 o# E- u
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks
1 k5 d. X* Z# H" H! r公仔箱論壇in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
3 t! n/ G  B6 Ayears old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
* W) p+ u0 f' Y  Itvboxnow.comunidirectional wind. The image above was taken by astronauts in the International Space Station in July.
% D/ p( b, V5 Q# otvboxnow.comIn the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.
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  c9 A  N5 H7 |公仔箱論壇The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
% _, a( D# h1 v+ ATVBNOW 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。geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it , Q0 v3 u& j; u( f  y. c
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
' {5 Y$ u# g0 [# M: T5 useasonal salt-water lakes. This image was taken by the Landsat 7 satellite.- h3 L6 X$ I( `1 z

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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact 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。' b% R5 Q9 g" O3 G" O/ W! n" e2 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。$ n5 |; R9 ^5 d- l
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide tvboxnow.com2 r/ y( _7 i& z0 b1 _$ B" L
impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a tvb now,tvbnow,bttvb- }/ Z. t( W; |) a3 c
reservoir and popular salmon fishing location.
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8 E/ I  B9 E+ J$ C, LTVBNOW 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  u. q5 z) i  j" c/ i, n

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% R* a3 w2 v5 e/ ^  RTVBNOW 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。This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was & [* v3 n: e5 P
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
) m$ Z4 v& w8 o! vlooking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood tvboxnow.com$ a9 \$ M, i% R4 p6 k4 o$ }, c9 O
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
; R0 h/ i% O9 E/ m5 \公仔箱論壇and 900 million years old and the raised area at its center is around 1,600 feet wide.
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The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
  \, @/ a- O3 Q; B7 Ntvb now,tvbnow,bttvbNASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satelliteTVBNOW 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。: @' X! t3 [' {/ y# c

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8 i) |+ L% ~8 t" s1 zTVBNOW 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。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, i5 ?( T, N: h
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8 W- w6 `; w6 V" ]" j$ aThe Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the tvb now,tvbnow,bttvb/ v. {0 Q2 `$ p# E  P
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
7 l6 z3 e5 u4 w8 ^  K  R3 CTVBNOW 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。grayish 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
; J( _& ?6 B  s, z( F' v公仔箱論壇simultaneously around 290 million years ago. The larger crater measures 22 miles across.tvb now,tvbnow,bttvb& b  y; k9 c& m5 G3 n# ^

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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 tvboxnow.com$ u2 j" f( S' A8 N0 X
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 boardtvb now,tvbnow,bttvb& T+ S7 |5 `. F8 \7 u* W
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
; Y# y; O% w: A  Mtvb 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
4 d# T8 e  z) I" z  s# R* E8 u$ X8 \tvb now,tvbnow,bttvbejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred 公仔箱論壇1 w2 l/ `3 `# r& \- Q
around 5 million years ago.1 W& W7 c5 ]  r1 Q

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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. 公仔箱論壇5 Z* u3 v& c8 ]7 C# ^& F
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, # u, U$ g' S2 K7 `5 |! L
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 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。! {6 i5 o8 g: [  R0 y
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s * o" ]6 q- \0 I
Terra 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.
2 G& u: q9 X3 Z2 T$ _2 H( dThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.) v  P5 @, [2 \7 e' S4 B0 T
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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 5 u* `6 i9 H( O
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. 公仔箱論壇5 @' }% P) ^/ E  e
Fortunately, NASA says nothing this big is headed our way anytime soon.