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Asteroid Impact Craters on Earth as Seen From Space

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Asteroid impact craters are among the most interesting geological structures on any planet. Many other
# f* \7 h, j; T& B  btvb now,tvbnow,bttvbplanets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
- B3 X6 M* X& D! f1 b  ~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。But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic tvb now,tvbnow,bttvb9 m6 a- s- z. ~$ G
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact 公仔箱論壇: U: v4 p$ l& c
structures don’t last long and can be tough to come by.
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. m' x! i' D( R, K1 Ztvb now,tvbnow,bttvbBut on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. ' @& Z% }4 ^0 l  `3 T
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here 1 c: A3 I1 l0 \0 N$ n# l! |+ @- b
show some of the biggest, oldest and most interesting impact craters on the planet.www2.tvboxnow.com# d7 _9 ?9 |) y# ~
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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% K& }( r9 i5 P
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million www2.tvboxnow.com3 @$ H% |  P' N4 e! x, z) Z" m
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent www2.tvboxnow.com! {' z: [/ C% w6 N
unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
5 k( k% ?3 t+ V6 s/ w# vwww2.tvboxnow.comIn the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.- d# {' d/ @3 O+ S$ z
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The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
1 T0 l7 \. @1 o4 Sgeologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it 5 J; Z, |1 [& g" ]
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
5 |& o6 {; S% D, m7 ]. jtvb now,tvbnow,bttvbseasonal 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。, N( k% d1 r' I3 A/ R9 S4 K0 l. i7 @0 }
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: E5 _" i& z7 s( }7 |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 Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
0 t. x& i* @* }7 ^: l; m. d  Ztvb now,tvbnow,bttvbaround 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around
+ ~. X8 z/ J9 Q' _  Htvb now,tvbnow,bttvb60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
  v3 ~. \8 u3 |# u公仔箱論壇impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
+ l6 R+ `) a  {. u) S8 [公仔箱論壇reservoir and popular salmon fishing location.1 A2 X9 M# G; f" [, Z

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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8 A3 t* M! I4 b' g5 [
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy . y8 p/ U" N+ f3 m' p
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 公仔箱論壇: L% t6 M% s- Z: n
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
3 q& G9 t) p! T' i/ ?$ T. yand 900 million years old and the raised area at its center is around 1,600 feet wide.6 K' p1 H/ }5 ^5 p9 i, A+ S

* ^- n+ P* v1 A; N& Vtvb now,tvbnow,bttvbThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
' R1 ~; D( U8 LNASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite
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+ M- c1 N4 I0 u0 @# j0 i; ]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 公仔箱論壇6 V( b7 L! i  z3 q# e- l! y0 L
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding 1 ?2 O( \$ `' ^
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.
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' n: k* J: S0 xtvb now,tvbnow,bttvbClearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred tvb now,tvbnow,bttvb5 x! W1 C% G2 B0 g, q
simultaneously around 290 million years ago. The larger crater measures 22 miles across.公仔箱論壇' {8 ^( W! V4 k8 v7 K
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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 ( z1 j+ }1 W3 [, ^
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
0 N1 M. p/ T( D. b! u4 `公仔箱論壇 the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
4 {. \- V% S$ _  T- [( |" i4 N& g( 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。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
  p% D' k. J! G1 bejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
8 o& K+ j' \: a% }' I/ x% Raround 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. ) J9 P0 I- M2 s
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, www2.tvboxnow.com$ A+ ~' K5 }4 k2 [, R
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. www2.tvboxnow.com% e8 Y1 \# [" W" h5 T; t: C) y( }
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
- Y: @  r% r5 C* _5 a/ BTerra satellite. It is a simulated true-color imagetvb now,tvbnow,bttvb' ?1 u3 s1 v+ I& I

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6 l* Z+ R; [1 G! @! ptvb now,tvbnow,bttvbThe Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
" O; r! v8 b5 r& [# \+ s8 i+ h1 iwww2.tvboxnow.comThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.www2.tvboxnow.com$ Z+ k+ C. N# J1 n8 l9 Q% u8 M
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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
2 C/ l- ^# ^5 k( I+ n, C1 |a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. 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。! v$ j$ n! Z" L) G
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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