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Asteroid impact craters are among the most interesting geological structures on any planet. Many other 0 |- ~! b/ t* p$ N, G" B
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
& V  o& ]$ P, ?1 U% S0 q( H- gBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic www.tvboxnow.com7 w9 C/ A  L8 x7 h( M
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
5 k9 S; M' o+ W, B  h: W7 @' U, D& ^7 tstructures don’t last long and can be tough to come by.' }/ S7 @; h! [: h
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But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. www.tvboxnow.com* I  R3 X+ u. H
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here
$ S8 N4 T6 d/ ^7 W" o+ Dshow some of the biggest, oldest and most interesting impact craters on the planet.! Z$ M) s9 }& z  d# Z8 Z' M

0 ?1 T( R3 X* f6 o- }/ }$ SAorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks
* T! Q" K& X( l. l5 p, L公仔箱論壇in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
: `' B% N, B2 b" A% u公仔箱論壇years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent * B+ T: N4 X: [7 ]% B
unidirectional wind. The image above was taken by astronauts in the International Space Station in July.
& @7 m) @. `1 Z. I+ JIn 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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2 r# Z) z& t$ K0 ^3 X! S% j/ G! P; a/ WThe Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
( I/ r2 b0 P# v: Jwww.tvboxnow.comgeologist 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。" p1 m1 r$ ?: ]3 X- e
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are www.tvboxnow.com, v! F9 ~' L' }0 C# w) l: c5 ~
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.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 i5 L! z1 h! @; M; {
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, }; V" |% {1 f, ~# }- C  E: iThe Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
% f" E) H4 I& c! ^) ~4 rTVBNOW 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。around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around www.tvboxnow.com5 H# \3 j. P; W* M0 u/ W/ e
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
, T4 q+ o8 r! H2 x/ D/ m; L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 0 s: S# B/ a% D' @: N" z& Y" i
reservoir and popular salmon fishing location.
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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
# I! K! i3 ?0 Gan impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy
) S8 u* @7 w' ]; X公仔箱論壇looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 公仔箱論壇0 w# u+ @! A6 J% m7 p1 K0 P
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
% @( n. \+ Y7 C6 s) q; ]and 900 million years old and the raised area at its center is around 1,600 feet wide.3 U3 L- U) S' o* r
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The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
# M& H5 L- H* {! l$ I$ n: J( e公仔箱論壇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
4 G, X. @. J! `' o* }8 pwww.tvboxnow.comcenter of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding www.tvboxnow.com8 P. r8 |6 y  L9 e- i1 I2 P
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.
: i* Q2 `2 r; l6 cTVBNOW 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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Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred 公仔箱論壇/ n' z; y: X$ f1 V
simultaneously around 290 million years ago. The larger crater measures 22 miles across.公仔箱論壇- U' T; x8 p" O) C6 u: s

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7 d- f, c# w, Q* VThe Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s
! }8 J5 y5 E' v+ m7 K" t* Ltvb now,tvbnow,bttvb1.5 mile-wide rim stands out as a bright ring in the lower left of the image, which was taken by a radar instrument on boardwww.tvboxnow.com8 x4 E) M9 H/ A0 x
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the ' @( i; H( D! s
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
+ w. }& w4 G% `6 k( F& l1 oTVBNOW 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
/ @* i  A, Q; S( Y8 v9 u7 ]公仔箱論壇around 5 million years ago.
1 U' @, \( T7 B- b8 ]) b& W公仔箱論壇公仔箱論壇# v+ N) {$ d" {1 K# a: e: y: B
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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. tvb now,tvbnow,bttvb6 L; a. Y6 n0 v, [5 ^$ w* W/ r
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
* @7 m/ T! {  {5 g公仔箱論壇a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
# B& O* R4 `$ g! J8 EThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
0 l# v) I; Q/ Q5 l* z( `Terra satellite. It is a simulated true-color image& Q5 {8 K) N9 e, Q" B" h& T
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( W( ]+ G/ |* S6 p( Nwww.tvboxnow.comThe Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth. www.tvboxnow.com0 J1 B" q: C8 K: e$ ?; P
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 {) Z  s+ n: KTVBNOW 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 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
* A: {& E# }4 Y$ L( ]  s/ Z公仔箱論壇Fortunately, NASA says nothing this big is headed our way anytime soon.