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Asteroid Impact Craters on Earth as Seen From Space

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4 @( E$ z8 S  W; Q+ M& u3 _tvb now,tvbnow,bttvbAsteroid impact craters are among the most interesting geological structures on any planet. Many other
$ e% d6 O5 S5 T5 x" P% M5.39.217.76planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
$ \5 D, v/ x9 r6 }4 l& [( jTVBNOW 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 : v% j: G: {# l0 Q9 _
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact tvb now,tvbnow,bttvb0 o) n& A, b, J! O1 A* W
structures don’t last long and can be tough to come by.2 P* A7 N) T0 P
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
! ?$ x" ~& X% \  n! ]/ H' j0 KOne well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here
% c) L4 W% `, I! _7 e% s4 z5.39.217.76show some of the biggest, oldest and most interesting impact craters on the planet.5.39.217.767 P/ L  g7 x7 S: `; x
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 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。% c3 W1 w0 I8 |$ w: z
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
: w- o3 ]% b& f公仔箱論壇years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
6 B! X) |- K6 `2 r! `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。unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
. Q1 h2 k& Q0 a# Z5.39.217.76In 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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The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 3 [6 R8 ]( s9 j0 q1 e$ I
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it 5.39.217.76% a4 j1 L* l( s! Q" q
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are " B, X# M9 L0 P/ I
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.5.39.217.76/ g  k4 e$ C! [' V, d7 ~
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' F: P$ {3 B' J. N+ j8 @tvb now,tvbnow,bttvbThe Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
& U* l0 d8 q! garound 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around
0 {( x/ c/ h3 R, G3 p5.39.217.7660 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
0 s1 t6 z! R: g! j2 Z; g0 Kimpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a 3 w& ?5 g7 ]% N0 w
reservoir and popular salmon fishing location.
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: d4 j  l2 x+ H7 q: t2 b  H4 a, Z9 qThis crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was 5.39.217.763 T1 p2 x4 u( Q$ j$ L  j2 C
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy - G( |; _  |: b5 \
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
# d! C" c. n4 M5 A$ f: nthe weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million : y9 B0 K& n4 ]+ C8 O, U
and 900 million years old and the raised area at its center is around 1,600 feet wide.公仔箱論壇: f3 n+ w. {! \4 a3 g

6 @; c% g, u8 w0 [tvb now,tvbnow,bttvbThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on , s1 [  q/ M; }9 M8 U
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite
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The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the tvb now,tvbnow,bttvb" @1 Q' _/ D3 f  p- |, \
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" A& K0 C5 @6 ~5 n3 b: p
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.; b& X* J; {$ M, |& m1 p" [0 o* W

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. L: \- R) b: a! z& J( l0 jTVBNOW 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。
' N4 l) u/ x; N9 P. X: Y; }) pTVBNOW 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
; W. j; X* O6 ]( B+ bsimultaneously around 290 million years ago. The larger crater measures 22 miles across.
2 f& S# e1 q1 ]6 \' Z7 fTVBNOW 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。
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- X2 Q6 ?' U' ATVBNOW 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 1 D, ^% z' J: d; t4 H
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公仔箱論壇+ n" s& H: U. i! H( l, E0 r/ ^
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
) A4 M- ]( B; O1 F5.39.217.76photo is a rocky hill, the darkest areas are wind-blown sand dunes, the blue around the crater’s rim may be material that was 8 D5 d0 q1 W' ?9 {4 E9 k
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
) n( e$ g# `8 Y. daround 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. . t: ^' c3 w) [, j8 k7 f
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, - c7 I' k4 r. E$ Q0 ^) R
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
" @, j4 D& v# \) I7 {% Q" atvb now,tvbnow,bttvbThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
  c6 h" E3 a  K, }% h公仔箱論壇Terra satellite. It is a simulated true-color image
0 R; |* m, t$ W& `/ q5.39.217.76TVBNOW 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。4 b; ~# y( j- p* A
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! j, X+ H- G( D; zTVBNOW 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.   S( W$ r6 E6 f
The 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
0 O9 W" U' p6 fa 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. tvb now,tvbnow,bttvb0 [) I8 p; t6 U4 A- p
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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