Asteroid Impact Craters on Earth as Seen From Space

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9 w. K1 o" Y! ?公仔箱論壇Asteroid impact craters are among the most interesting geological structures on any planet. Many other , Q: X0 g" z- l( F
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
# [7 S$ g+ ~2 @+ U+ A% P% NBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic tvb now,tvbnow,bttvb+ B( T$ `* m3 y" `
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact # f) R1 X0 R( c: n% C
structures don’t last long and can be tough to come by.
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here tvb now,tvbnow,bttvb7 X$ s' P- y2 }) |! g0 v' _/ q4 Z
show some of the biggest, oldest and most interesting impact craters on the planet.# c: ~( m; y) l8 _- O4 K! B: y

  P) P8 s$ w9 x7 U% l0 w1 p4 lAorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 公仔箱論壇) c# {  ]/ u/ D: \8 x
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million 公仔箱論壇2 L9 [; V, Y9 b9 j: {; ~
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
+ A9 ^# ~) \9 {; L6 ^" x公仔箱論壇unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
+ m$ D7 K$ c; A6 t3 t1 IIn 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
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it 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。% X* s9 C; h  F. p( x8 J9 e' z6 e
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are ) T/ ]$ r+ ~) G' L
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.公仔箱論壇5 e+ j# L) L& ?8 h6 s
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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
- E9 P( e# u' W$ H5.39.217.76around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around 5.39.217.767 F4 o' k# h4 b. O# N1 {
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
& [1 ^' l9 V/ }0 H/ D3 Freservoir and popular salmon fishing location.tvb now,tvbnow,bttvb$ I2 A# M/ `$ v; m
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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was 5.39.217.763 w6 Q$ N7 m% x1 D% i" L/ d& x1 k
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy 5.39.217.76  ?9 O* K) R: l3 j
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 公仔箱論壇/ D: y% l+ _. [6 T! N( g! j
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million 4 l( _" _. P# k$ k+ U
and 900 million years old and the raised area at its center is around 1,600 feet wide.
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( S# L0 v0 I% B/ G' GThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
9 c/ W3 A8 q7 {: _5 Z  aNASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellitetvb now,tvbnow,bttvb" }/ Y6 T/ Z/ A

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. K+ b; R# C+ o, T/ b. V3 c+ BThe Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
" R: N4 d" |9 Q' B0 @) l- Wcenter of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
6 q+ K/ D" C. z8 N; u, P" ?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 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。7 U5 V! ]2 J9 e5 d& @
simultaneously around 290 million years ago. The larger crater measures 22 miles across.
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# m- B( C6 M" l5 v5.39.217.76The Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s
$ _( ~' a- Q$ J5.39.217.761.5 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
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the 公仔箱論壇$ o! [2 t' ]* ?. G0 a1 v
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. Y6 [: A1 `ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
1 i! e7 F( t" a. K7 Z1 u5.39.217.76around 5 million years ago.4 Q5 x0 M  `0 a
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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。3 @9 q% B; I1 H: b( I# Y
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, tvb now,tvbnow,bttvb9 Y  [1 ^2 M/ ~3 T4 M* B3 L, y
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. tvb now,tvbnow,bttvb. i. @% r& x& ^: v
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s 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。# z7 K9 |* u! ^, R# Y8 F
Terra satellite. It is a simulated true-color image
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* J3 v! x8 A2 `: o" @- g3 r+ XThe Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
The 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.tvb now,tvbnow,bttvb! e& H1 e+ x) B/ _

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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. ~+ s* K: R, q3 f- d( fa 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
+ F+ d3 W$ G4 j' l6 h5.39.217.76Fortunately, NASA says nothing this big is headed our way anytime soon.