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
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
/ \2 F( W) M' [* s( Aos.tvboxnow.comBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic 3 |7 q. r' ]  Q. H& c. l' U4 }
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact 公仔箱論壇# p: X  `- K/ Z5 {& e
structures don’t last long and can be tough to come by.os.tvboxnow.com1 V1 q* B4 w, Y, @' W4 J

/ I' d: h/ S, q- W; SBut on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. 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。) I0 q! j' v: H0 \" l
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here os.tvboxnow.com, i& q# Q! g1 J8 e& f
show some of the biggest, oldest and most interesting impact craters on the planet.

0 M* ]& y2 T- ]! O* w) {Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 公仔箱論壇" Q! Z9 e0 r! ~  r* m) C
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
. t* S) p# E; O8 p# L# F0 Yyears old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent tvb now,tvbnow,bttvb7 }; \$ X0 \6 t! z( c
unidirectional wind. The image above was taken by astronauts in the International Space Station in July. tvb now,tvbnow,bttvb( O4 j( q+ }1 u0 r+ l( z% t2 u
In 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 os.tvboxnow.com: q7 \$ i, L3 K5 k4 ]7 q6 Y
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
( o0 Q9 ~' T/ jos.tvboxnow.comcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are 公仔箱論壇! ?# O. l5 S6 t: V& ~1 N. R
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.

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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
2 P( j8 ]) I1 C. }" Haround 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around
( f. N5 |& n' s. H/ u6 m60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide 6 A* t/ {4 `3 V+ U
impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a ) t5 m3 ]) e/ t0 Z( {# ?8 f5 @" l
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 公仔箱論壇- K0 I/ v1 T' {* g+ Z4 s
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy os.tvboxnow.com' _1 o& v& i- p. T
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood ! X' G! l1 k% i) f# A& q, G
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million
& \( s* d: a2 |! yand 900 million years old and the raised area at its center is around 1,600 feet wide.
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The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
+ N8 ]4 \" ~, {NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite8 W: g4 X' c) i4 a
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2 B: |% l8 @3 ftvb now,tvbnow,bttvbThe Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
) z& R, _$ R0 @8 m) w! i, ?" ^center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
$ Y; M! s8 E" d. Q2 }& y/ Ugrayish area. The crater was formed caused by an asteroid impact around 140 million years ago.# K1 H( g5 F- V+ N

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$ m8 d; V* W& Z9 R7 X* ^Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred
simultaneously around 290 million years ago. The larger crater measures 22 miles across.
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" b* T4 L% m3 i) s8 T, rThe Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’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。. p+ C( _2 T" y3 f9 L* V$ k
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
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the 5 O' l7 Z7 X! W" W, I
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
" x& X& l  f% jos.tvboxnow.comejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred 公仔箱論壇+ {; v; D. w/ S  o' t4 h& G5 F4 w
around 5 million years ago.! y0 s) g. w- y7 _3 d
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9 K8 x: P3 G" G9 T  KThe 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,
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. 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。( q& r7 A/ A3 l! [, H, \
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
Terra satellite. It is a simulated true-color imagetvb now,tvbnow,bttvb" X! w, K( }  _
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The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
) J9 M. d; Y7 P7 [; FThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.: m  |& b3 J" i) X% C% T6 G
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. `: I: p0 y; e% V) wos.tvboxnow.comArtist’s rendering of a space object or phenomenon, so we couldn’t resist this beauty. This is one man’s idea of what os.tvboxnow.com- Y2 o) `; r8 k3 c6 F
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet. 8 e/ w/ ~1 e. {# a
Fortunately, NASA says nothing this big is headed our way anytime soon.