Asteroid Impact Craters on Earth as Seen From Space

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; `4 \% n$ S- x( i5.39.217.76Asteroid impact craters are among the most interesting geological structures on any planet. Many other 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。' i) w5 k, D7 z: j, g: z
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
% V" P8 m8 A. Z# H6 q8 `4 s$ ]tvb now,tvbnow,bttvbBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic
6 J1 E6 g# Q. }! Rtvb now,tvbnow,bttvberuptions, 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。3 d0 E) D% n' `8 p( p. ]* P1 h8 c
structures don’t last long and can be tough to come by.; v' ^$ ?+ p1 E: ]- U- A0 F
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. tvb now,tvbnow,bttvb/ m" b, M4 [$ b5 q
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here
8 X4 v) {$ _/ \tvb now,tvbnow,bttvbshow 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
0 C: M0 I2 r" ^7 U6 `2 M& 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。in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
& h( S5 w: a) z. [; V* h5.39.217.76years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
  ^. G' H3 M% Bunidirectional wind. The image above was taken by astronauts in the International Space Station in July.
, W. k3 c# J* G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,bttvb- ~( L. c3 q- N$ U

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  U  y2 ^, H) _: f# N1 w6 q公仔箱論壇The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 公仔箱論壇  p+ k/ u9 D6 H$ o: g( O
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
( A/ f& ?3 _& l9 C! {& H8 T: O8 Vcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
, x" f6 ]' e; F# l5.39.217.76seasonal 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
$ P! }6 o, ~; ?) }7 daround 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around . H9 p  |. K1 T, b  m& n' E
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
' @: r; v; Z. D6 k% a+ W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
1 Q. u7 y; t% k$ j9 _reservoir and popular salmon fishing location.公仔箱論壇0 q3 D3 I6 r; V, r8 M* @
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1 r/ `: W  c& s: ]+ _. ~, ^tvb now,tvbnow,bttvbThis crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
4 A% r6 C* ]/ r4 v0 w# M  Xtvb now,tvbnow,bttvban impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy 公仔箱論壇4 D; W& x/ Q- |0 t3 B: s
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。( F& T( q8 V8 M/ N& W4 V8 y! l
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
* T4 g% o/ t& Y" @. I) iand 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。  T3 H7 \$ D8 b

2 q2 a$ Z% i1 x# 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 image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on 5.39.217.76% G! T8 N! C( s0 l8 c! W- n3 }% x9 i
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite5.39.217.766 O! A) l5 z( F

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The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
8 `; K- Y( I. V1 `) d2 w' D2 c/ Dtvb now,tvbnow,bttvbcenter of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding / W8 c2 R' C5 j1 F% |# P5 P
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.
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4 U6 O1 Q$ [. X) r; K5 ?tvb now,tvbnow,bttvbtvb now,tvbnow,bttvb! f8 ^3 C# K; F! B9 W. F  U5 u

! [% a5 l0 t% ]7 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。Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred
6 U! Y  |  {4 ~$ bsimultaneously 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
9 q- r9 p% ~5 ]7 y; X+ YTVBNOW 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。1.5 mile-wide rim stands out as a bright ring in the lower left of the image, which was taken by a radar instrument on board5.39.217.765 Q5 i, A1 F* w' N6 I: r) ?. c
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
) _( b. S( @$ x% z* g0 Yphoto is a rocky hill, the darkest areas are wind-blown sand dunes, the blue around the crater’s rim may be material that was
- {3 }/ n& h2 Z2 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。ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred % ?* ^3 U9 O; x0 t2 A8 y
around 5 million years ago.
* |( C) M# }3 n0 s" c! r3 b$ [$ nTVBNOW 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。2 F7 q% ~* W# @  D% Z$ K
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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.
: Z- A0 r) q5 }tvb now,tvbnow,bttvbScientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
2 a* b  C9 F: P! q! I( V3 E2 W% i2 X$ s公仔箱論壇a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
; |4 w6 n, X) q9 Q- R. s! Q6 _This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
* M9 ]* d' M/ J5.39.217.76Terra satellite. It is a simulated true-color imagetvb now,tvbnow,bttvb3 C  `) a$ x& p' e) T
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1 L4 e! i  y- d5 _5.39.217.76The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
$ ^. t+ D5 l' h) O4 P2 _; z) mtvb now,tvbnow,bttvbThe 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 公仔箱論壇; S. C$ w- W' T
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。% {  b8 a$ b# z. E) ]: U+ W
Fortunately, NASA says nothing this big is headed our way anytime soon.