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Asteroid impact craters are among the most interesting geological structures on any planet. Many other
$ h1 l2 O- ]- T" I7 fplanets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
8 }" U: n& }, {2 l0 {公仔箱論壇But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic
4 q% j0 J8 H1 s) A& T0 zeruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact 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。# Y" k" R7 m& W' O" h$ L2 E7 O
structures don’t last long and can be tough to come by.
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. 公仔箱論壇6 j+ }$ C" D7 e' a! R
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here 公仔箱論壇/ T7 v7 D% G# {9 C- C
show some of the biggest, oldest and most interesting impact craters on the planet.tvb now,tvbnow,bttvb6 E1 F' J- v/ M5 X
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks
2 e: r# O0 ^. j% X9 w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
8 }1 T/ _) l; K/ G& y5 ~/ _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。years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
- H3 F/ k, U8 k" g: r3 munidirectional wind. The image above was taken by astronauts in the International Space Station in July. www3.tvboxnow.com9 u9 g& }) N: f; d! G" K: q
In 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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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。/ h2 d# c: e3 m) w4 O6 t

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2 z: k) t0 r0 O: h8 S1 l6 H$ c9 iTVBNOW 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 Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
2 p' Y/ Y4 a8 I" Itvb now,tvbnow,bttvbgeologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
# t2 |( w/ x1 j: E1 Qcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are tvb now,tvbnow,bttvb# W2 y6 E3 v  v! d
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.
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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
( G2 J6 k0 ?/ j  t- K* htvb now,tvbnow,bttvbaround 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around
) {! ^. R4 S: Y6 }5 n0 D2 S/ Z; Uwww3.tvboxnow.com60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide ) V0 n) p( ?% y5 m
impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a 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。# }( f0 l3 m# ?& z
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。8 y0 H: m! u+ I- U
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5 S* z% {" Z! c: I2 Z& |8 rtvb now,tvbnow,bttvbThis crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
7 n; ~: F0 R; L7 r/ m* R- Ban impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
% p. z7 ~, z# t5 [8 ~/ Q1 dTVBNOW 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。looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 公仔箱論壇6 u0 X: p) Y8 K# f; p6 O: }0 N
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
/ U+ l4 N0 A8 B6 f! @! T公仔箱論壇and 900 million years old and the raised area at its center is around 1,600 feet wide.www3.tvboxnow.com, q6 J" p2 @/ \: q3 X

2 V- \% W8 n6 m# z8 I' NThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on 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 I, ]2 ^# \8 a. f9 g2 F' u: q
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellitewww3.tvboxnow.com& g' R) J4 i/ o! F9 q
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+ i5 Z; e! Q+ X8 o. j" |+ F9 }3 q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 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。( [* t+ s+ l7 Z7 y; N6 a
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
" P  p  P2 ^! [9 s- @. Egrayish area. The crater was formed caused by an asteroid impact around 140 million years ago.) s9 M/ h5 I: `1 z0 M% T; |

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Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred 1 `3 C4 h. O* I: Y7 ~. Y, l
simultaneously around 290 million years ago. The larger crater measures 22 miles across.
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6 N* p7 s2 d) T( W5 y8 X9 Q3 l* {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 Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s
$ C; B- N, _; \+ O% @tvb now,tvbnow,bttvb1.5 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* k3 k& {- Y' I. w- C3 A
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
% f6 }! ^3 ^( m+ Rwww3.tvboxnow.comphoto is a rocky hill, the darkest areas are wind-blown sand dunes, the blue around the crater’s rim may be material that was
. g0 Y5 S+ C8 e- c8 }tvb now,tvbnow,bttvbejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
1 w" B5 g, u* \+ `6 i- v/ ntvb now,tvbnow,bttvbaround 5 million years ago.
) f1 e6 g* k! @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。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' v' _! [5 G' v- t! a5 x
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。; P9 A& _+ A2 r0 y
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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) k' H+ e5 f公仔箱論壇Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, + c' {; ^) @: k4 @! a
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
9 _& h" o: b5 V6 b9 eThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
6 t, Q. N3 w7 A# l4 o, Q' B2 tTerra 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。9 R: n6 w' N9 `! w& L( w
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& n5 [5 E7 r8 r* dTVBNOW 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 Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
0 }. J6 u0 V+ `' D% ]www3.tvboxnow.comThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion 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。: c7 V! |8 h: O" N' v8 G2 }

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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 www3.tvboxnow.com( N, R! R2 V8 O2 V* j
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. www3.tvboxnow.com/ j! i/ z5 r* O; @
Fortunately, NASA says nothing this big is headed our way anytime soon.