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 H) [/ ]7 ^8 ^5 G8 A/ h

" H& Q% A+ M' Z% x公仔箱論壇Asteroid impact craters are among the most interesting geological structures on any planet. Many other
% }: j* p7 S' x6 B) Stvb now,tvbnow,bttvbplanets and moons in our solar system, including our own moon, are pock-marked with loads of craters.   i# d! c! F5 K
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic
  [8 ^, ]+ l; e7 [4 Yeruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact ! \3 I2 n* [. |- @% Z/ q5 {
structures 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。- ]0 K* K% X& @- X* y" d& R+ |
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. os.tvboxnow.com: h2 w8 K! _3 p9 \8 x+ c
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here 公仔箱論壇. a5 t% }" |. \; D8 r
show some of the biggest, oldest and most interesting impact craters on the planet.
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5 H) [9 P# K2 n# r9 X' i1 HTVBNOW 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。Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks os.tvboxnow.com' J) H/ N8 ?( ~) b
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million 公仔箱論壇" l4 h1 y2 E/ i! m+ {
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
7 t; O4 j8 }8 Y: s2 g公仔箱論壇unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
. D/ x1 }: Z2 r& |os.tvboxnow.comIn 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。: [/ [, z& q5 u5 q
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+ n% M, [' N( ^% g+ los.tvboxnow.comThe Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
2 A6 n! x/ J6 e+ z$ W2 ?) |1 M5 XTVBNOW 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
) D8 n" F3 p3 O+ x3 B, Xcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are 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。' E+ U6 C5 F3 V" U8 u
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.
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' v- `' ^! K; M5 H! iThe Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
" a( c$ o  v0 G3 L+ ^! oTVBNOW 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 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around 公仔箱論壇% ?% H, S- Q4 u! X% Z9 a2 m
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
1 [3 y9 @% [  e" j" yos.tvboxnow.comimpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a os.tvboxnow.com. S% N8 F9 I4 W: Q$ V$ @, Z' m" [" P
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。9 Q4 |- J1 `" ^

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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
) c8 m! Q- ~! h5 j+ [+ Itvb now,tvbnow,bttvban impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy ) W, F, c; N& W" L4 K
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
' h' K- x" c7 W" v& E, o( ~6 uTVBNOW 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。the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
9 h: e0 j- @4 g# v0 [' f' U1 Y7 W; R6 E公仔箱論壇and 900 million years old and the raised area at its center is around 1,600 feet wide.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 ^2 _: D) g1 `, b5 \
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The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
  U2 O8 _9 \" ?1 Q* C7 i公仔箱論壇NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite
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( @* j8 O; S1 \; ~% e. S5 E! F公仔箱論壇The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
$ g' r* J3 p( @1 F1 ^$ `* N* n" Ncenter of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding 公仔箱論壇& o- J, n4 X) A. ^! c8 j* T5 h- p
grayish area. The crater was formed caused by an asteroid impact around 140 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。6 v& j5 ^/ \3 }! H- x  [* n
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Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred
2 J* S" k( S5 ?0 j; isimultaneously around 290 million years ago. The larger crater measures 22 miles across.3 ^* L- [& V+ M
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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 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。. v7 s% g3 V4 w& n9 y% 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
' P+ w) c  t" {5 p& n' }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。 the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
9 K$ I6 \% f  W$ l" z公仔箱論壇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 公仔箱論壇3 e% H7 h! `; M6 O9 l/ \; z
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
$ C! ^# }4 u3 j" c  g. O3 karound 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. $ B% R* l/ J% U4 {. Q( g) s
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, 0 D, y8 j5 A4 N0 l/ g
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
; }( U; n# z6 dos.tvboxnow.comThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s tvb now,tvbnow,bttvb7 _) a1 u( ]3 Q
Terra satellite. It is a simulated true-color image- k; ~8 Y+ Z6 a

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The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
, h: N! _7 E& @. BThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.os.tvboxnow.com1 s, d: p! }0 r- a

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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
& w' N7 e/ ]1 I8 {8 ua 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
( e' Y& p' D( Itvb now,tvbnow,bttvbFortunately, NASA says nothing this big is headed our way anytime soon.