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Asteroid Impact Craters on Earth as Seen From Space

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9 y( A" R. f1 S( m  D7 ^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。Asteroid impact craters are among the most interesting geological structures on any planet. Many other tvb now,tvbnow,bttvb5 |9 E1 Q+ N9 [: \
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
' X9 T6 d" g: n5 E- c; A3 ztvb now,tvbnow,bttvbBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic tvb now,tvbnow,bttvb9 a1 G5 _9 h- d" i
eruptions, 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。0 P8 x1 h6 R& N- B, [7 C/ \
structures don’t last long and can be tough to come by.$ j/ {' ?( _. @' P; q5 }
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
, L- z8 A7 G& B$ G6 YOne well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here
2 P0 s1 V1 }6 r- |* ~7 fos.tvboxnow.comshow some of the biggest, oldest and most interesting impact craters on the planet.
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 公仔箱論壇4 D) D8 p& g* a- O* O, g
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million 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。& ]  `1 l3 m4 c/ c
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent tvb now,tvbnow,bttvb# @, W" B$ ]  Z( w" d
unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
: l$ }1 g" M/ _% f7 L: S- b( W1 r. T公仔箱論壇In the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.tvb now,tvbnow,bttvb5 I, q& M6 t* w3 I) o5 O$ g: l
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The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 公仔箱論壇5 S4 M& J5 c% {" F
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
! e6 l. x( q5 @/ u# h1 @tvb now,tvbnow,bttvbcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
, m9 b& Y5 \& V. ~1 o2 N公仔箱論壇seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.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。1 o+ X$ Y$ A: v
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2 h& M% _/ E& N. w: ktvb now,tvbnow,bttvbThe Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred # w+ o$ F& Z: M: h: Q" [; J
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。( x5 K( w: a* Z) n+ e7 I- B
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
0 Q4 F: Y2 H# i& f# n8 [7 Itvb now,tvbnow,bttvbimpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a tvb now,tvbnow,bttvb8 W8 c, v- G4 i0 u( Q# J$ w
reservoir and popular salmon fishing location.公仔箱論壇" v0 \7 i: }- E, j$ O) d2 x
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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
4 L7 e+ _( H: q) S' a) p1 N* vTVBNOW 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。an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy 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。7 l" l( b5 e- ]
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
5 ]) w) z' c: n9 g* L" W% s9 eos.tvboxnow.comthe weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
1 a9 s' J, D, ?0 A6 x9 ^" land 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 os.tvboxnow.com# v& j6 r& S& Z* a- ?
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellitetvb now,tvbnow,bttvb3 l: n6 Q& F; F8 R% \
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( Z0 G9 r2 ^" p1 p2 w# {, U7 L2 v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。0 H7 f/ d& b: L8 R. |$ g
center 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( D8 R' @7 K9 b) n0 \& \
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.公仔箱論壇* r+ d. Y/ W1 s3 I, K) z1 o6 M, R

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/ S# N* A/ z6 n" ^5 h; ~6 `, ]tvb now,tvbnow,bttvbClearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred
% `+ s6 N! k  o5 \% V/ q公仔箱論壇simultaneously around 290 million years ago. The larger crater measures 22 miles across.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。. R. S  n/ n4 ?6 c* V
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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
) E: Z8 ]+ |- p3 ~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 boardTVBNOW 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 N; X- W( J& D& I
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of 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。5 t  S2 }6 s/ G& {3 Q
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 , J0 l' t( R8 P2 Z6 ~
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred tvb now,tvbnow,bttvb$ C4 R4 n  }% G) A' o8 n
around 5 million years ago.tvb now,tvbnow,bttvb+ u' ?7 e) B! I! b1 O1 \
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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.
- T- P. A: Y. @公仔箱論壇Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, 2 c: _" R. m7 U4 l; z+ |! y0 ^1 w/ B
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. * N. R* Q6 X+ a6 f1 X' u
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s 公仔箱論壇- I$ ~# R  `1 L
Terra satellite. It is a simulated true-color imagetvb now,tvbnow,bttvb4 E8 i. W8 n& J) ~9 _$ y; |0 W! q

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. y* m: ]2 K' A& D7 K0 Y) O' rThe Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
+ x3 E- \7 [) f6 h  ^  D公仔箱論壇The 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.
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2 I% H' W& S  b9 K; `' b5 b8 ]tvb now,tvbnow,bttvbArtist’s rendering of a space object or phenomenon, so we couldn’t resist this beauty. This is one man’s idea of what os.tvboxnow.com3 w' U4 h. x  R) f
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. os.tvboxnow.com8 M  D% {) c* }0 u
Fortunately, NASA says nothing this big is headed our way anytime soon.

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  • k23bb

真係厲害好少見
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