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Asteroid Impact Craters on Earth as Seen From Space

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( I5 o3 D2 L+ h9 H! P2 W# q, r  z3 ?Asteroid impact craters are among the most interesting geological structures on any planet. Many other
0 u; @" ^$ N! u& k7 Z6 Gplanets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
+ @0 |# P) ?1 ~& f' \6 ?; G- |But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic
, V, x7 @" Q. T( ?eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
1 L& F  `! i3 h9 Y, X6 b) {; gstructures don’t last long and can be tough to come by.公仔箱論壇( z' [( o, i/ x: p$ F! T

' }: p9 u7 R* o. c5 E. m5.39.217.77:8898But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. / _( Y8 S2 @9 b' Y7 o& z$ q( d; c9 E
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here + N- z. U7 h( p
show some of the biggest, oldest and most interesting impact craters on the planet.tvb now,tvbnow,bttvb/ ^0 H) H6 Y; j$ H  f7 `) Y
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks tvb now,tvbnow,bttvb5 b4 _& I. B% U, [  R
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
# |. n8 t* R1 L  q( f, ?years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
: v, Q* ~/ X% U5 ^. Eunidirectional wind. The image above was taken by astronauts in the International Space Station in July.
3 U3 j( N/ S6 z- O2 ^In the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.5.39.217.77:8898, Y' S( O4 n6 T! E; z; i

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" J8 a2 T+ V2 L0 i& ~- }tvb now,tvbnow,bttvbThe Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
" r) S2 h3 M6 |5 ]. |3 a8 ?/ gtvb now,tvbnow,bttvbgeologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
  E/ J1 y8 T( t+ P+ `8 Ucould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are   T4 @3 r( C& X2 e% A9 I9 F
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.公仔箱論壇/ W% S: g& _+ i5 A
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7 s5 _6 Z  ?% I! K6 }% Y5 uThe Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
7 W/ T: ]; n: H公仔箱論壇around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around 6 ^4 m. W$ c5 \% y$ d& ^2 \+ E
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
: u1 u4 H( \- y9 p, u2 Nimpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a - j( C4 {, r5 `9 @( @2 U
reservoir and popular salmon fishing location.7 w5 y) I/ A# ]7 @* H
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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- f* D( V" g0 m! `! ]9 B
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
* J  p! c9 E5 W, [; W% eTVBNOW 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。looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
5 R5 G5 G7 R2 K+ q# I1 d  P4 }/ w公仔箱論壇the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 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。$ @; e7 _7 t% w) c' U
and 900 million years old and the raised area at its center is around 1,600 feet wide.: R1 D7 E  Z$ p( P; B

! y; f1 Q# B9 ^. w# oThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
# r2 L6 }3 |7 n! q0 Q% W! Z5.39.217.77:8898NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellitetvb now,tvbnow,bttvb0 Z; R3 R0 K: X5 l3 v5 w

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The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
7 t7 {% s( V+ b, k, n  y# Ncenter of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding 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。' d. F7 G5 {% T5 S" T$ ]
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.
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Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred 5.39.217.77:88980 b9 m9 _6 c( R9 G, |' r5 A* v
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 8 j& y, u. M- n
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
2 {8 Q' U7 L) A) s' G/ c/ \2 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。 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/ R- A2 |3 N- F$ d' x$ O0 [  T
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
  S% U$ }) ]' }! a5 V  Wtvb now,tvbnow,bttvbejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred ) C4 Y! Y! [- l8 f$ ?
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. 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 |9 V; t4 [8 y6 @7 ?
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
6 g" Q2 j$ d: S" O7 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.
8 u. s7 O' L; W" i9 k# Z: m  Atvb now,tvbnow,bttvbThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
. I2 b- g( ?" g) l! W* @  ITVBNOW 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。Terra satellite. It is a simulated true-color image! R' U0 O! s! A# n0 I" W

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; ?* G9 I& i% ?2 d+ \& e9 H7 e5.39.217.77:8898The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth. 9 I0 E; _) Y0 j4 W9 S0 v6 r2 Q8 H! s
The 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.
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" g( e2 @7 E$ c: |3 J; 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。Artist’s rendering of a space object or phenomenon, so we couldn’t resist this beauty. This is one man’s idea of what ' v% Y) I! d$ H4 `
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. 公仔箱論壇5 }1 D; N* g$ z# H
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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