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 tvb now,tvbnow,bttvb- ^7 y) Q! U- x3 w
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
" M3 E9 n) E2 b. x- UBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic
1 D. o/ T* t0 ueruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
structures don’t last long and can be tough to come by.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。1 Y5 ^/ o* P  ~% Z. R
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. 1 v' w7 U' m8 `! p' s
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here tvb now,tvbnow,bttvb, {1 h5 `- d* p
show some of the biggest, oldest and most interesting impact craters on the planet.; U; v; D: r/ n  h( S8 @# z

7 R* \; |( ]- K; Qtvb now,tvbnow,bttvbAorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 公仔箱論壇& `6 q$ v5 c' O8 I% D, f- w8 l5 V
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million 1 X) G. G" m7 b
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
# G4 o# L- t& W1 }, t+ a( wunidirectional wind. The image above was taken by astronauts in the International Space Station in July. 8 U9 h) Q/ j2 @
In the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.公仔箱論壇! J4 s: c- {5 l( ?( Q% \% G
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The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 公仔箱論壇: m7 V) a* L& _
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it 5.39.217.77:8898; {  j7 J, W/ A8 W
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
- i) L( e3 I2 e8 j" N2 ~seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.tvb now,tvbnow,bttvb" A4 F0 ~6 b5 |0 S4 F) m% L

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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
  F' A% ~" y+ _( ?5 _+ iaround 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around 5.39.217.77:8898, d! g+ l! M1 {6 w" ?6 D3 `
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
) F8 K: Y& T! `0 ^tvb now,tvbnow,bttvbreservoir and popular salmon fishing location.tvb now,tvbnow,bttvb, A- w# b; x% r% q. p: X* _

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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was 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。: `+ O, O* O4 m- z" c# z3 j. P. W
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 3 |+ }3 P5 ?/ m
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
" ]  Q: Y- N4 M# vand 900 million years old and the raised area at its center is around 1,600 feet wide.tvb now,tvbnow,bttvb% ~& J/ t% F6 R9 M/ R( S

; h% x! {6 R9 pThe image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
7 A* H' L6 v# K5 U5 s! nNASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satelliteTVBNOW 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。# a; {) q. D2 `2 L- _) f, u

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( `& L: w# z0 O8 Z" {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 5.39.217.77:88986 {, R4 T7 ?* V- ?8 H
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
2 j  X& \% z( i" }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。& \# B, `3 p# m4 `8 m; u$ Y
simultaneously around 290 million years ago. The larger crater measures 22 miles across.5.39.217.77:8898! \" p: _) S& y" G: T$ k) S
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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 公仔箱論壇# T7 L3 [4 h! I/ k0 e8 e) w' D
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
, t' z5 y) k  A4 T the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
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 公仔箱論壇  J& ]' o; ^7 Z2 s
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
around 5 million years ago.0 F5 _& D6 L1 U# E6 u0 w

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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.
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, 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。# m* j$ N. h& Z8 y) j! U! q& |' k9 F
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. 5.39.217.77:8898& w, w4 ]+ S1 r9 Q! P
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s - s2 a1 f, _% j
Terra satellite. It is a simulated true-color image

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The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth. 7 s' O( v3 U7 z; ?
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 & |7 F# Q5 `4 ^3 J' \
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
Fortunately, NASA says nothing this big is headed our way anytime soon.