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Asteroid Impact Craters on Earth as Seen From Space


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. Q$ p4 D! [: Y( P( G8 S( X& awww2.tvboxnow.comAsteroid impact craters are among the most interesting geological structures on any planet. Many other
5 X! G; ]4 O3 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。planets and moons in our solar system, including our own moon, are pock-marked with loads of craters. www2.tvboxnow.com& D* u( C' f  l0 w" g7 k( ?
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic
" u9 c! B0 b9 l3 M7 Kwww2.tvboxnow.comeruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
- @7 l, n5 m5 i' q4 Wstructures don’t last long and can be tough to come by.
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# w+ ^9 o' t3 m; }+ z. j) E; C) JBut on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
; m# P& A, n/ H, qOne well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here # F3 q& }2 k" {! [7 Z/ Y: H
show some of the biggest, oldest and most interesting impact craters on the planet.www2.tvboxnow.com. O; m# c" n+ p) t

7 P1 O% E9 f7 ~! a! bAorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks
. i3 T; P8 R  _2 j- xwww2.tvboxnow.comin part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
/ w  u' F3 R1 A- D% ztvb now,tvbnow,bttvbyears old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent tvb now,tvbnow,bttvb; ], V3 f5 z* g# F7 Y4 i" B
unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
' Z6 V* s% U  p+ iIn 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,bttvb; ?9 k# L# q/ L8 C$ r
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The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
8 U9 t1 o: g' I1 k0 mtvb now,tvbnow,bttvbgeologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
* z+ [4 W4 u0 `% n" }tvb now,tvbnow,bttvbcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
+ {1 ^1 M" G2 J4 Rseasonal 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
8 k: f/ z# ^9 O1 n1 Varound 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9 c7 f; f$ L7 P1 _2 q  m& _
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide 公仔箱論壇! q" B: j+ ^( O# Y- m' y  h/ K
impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
" F5 l/ a, `; mtvb now,tvbnow,bttvbreservoir and popular salmon fishing location.$ U2 o; I$ }: B; }$ P$ M$ U5 U
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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was 公仔箱論壇$ s# z& F6 s. ]5 X8 C
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。, y& T* n5 O) M0 W( L) b
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 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 y, O+ o/ q1 E$ b$ U
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
& Q) E6 T$ I5 [7 k( O! J' Uand 900 million years old and the raised area at its center is around 1,600 feet wide.' U. w/ l, [, |

" s3 d5 x! b3 [$ X$ @! PThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on 公仔箱論壇$ j3 k" g! u# g. }$ h0 u6 I  D6 e
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite公仔箱論壇0 r! f' m; ]3 z5 z
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The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
: Z% L3 n. L' H$ L2 h: v$ W) `www2.tvboxnow.comcenter of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding : ?3 O* E5 E5 O! R2 g
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.tvb now,tvbnow,bttvb1 r8 X' `4 O, O6 a+ K
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Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred 0 x, U9 S1 W6 c' I& ?
simultaneously around 290 million years ago. The larger crater measures 22 miles across.
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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 公仔箱論壇8 G& z  {2 \$ B4 x2 a: g& T
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) [" ~, v* ^9 u4 @
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the tvb now,tvbnow,bttvb/ v6 B& b0 a, x. y4 A7 _
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 1 P; y4 z: C7 y* h. Q& M
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred tvb now,tvbnow,bttvb6 K% ?1 r, ]& G  f& B& [
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. 公仔箱論壇4 y! Z) X7 Z) ~; r; {" m0 t
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
- [% H4 ?$ c! }9 I- J( Aa glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
; U: o: r. V3 h, |* CThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
- p6 l% f( b/ f) f, z, ~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 }' D+ Z" O& E& d! H! X0 I9 k
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7 b) }9 L; v: Y7 f6 L( Z  U, nwww2.tvboxnow.comThe Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
8 h3 J- [" H6 B- E- y  T  |www2.tvboxnow.comThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.
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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
% u) ~- c* g7 ~, ?0 ]+ J0 \www2.tvboxnow.coma 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. www2.tvboxnow.com5 o* U) e9 X( x1 B8 @3 Q2 X' k
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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