Asteroid Impact Craters on Earth as Seen From Space

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; \3 L; w; w, S6 G! b公仔箱論壇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. 7 F& p! x9 u# V" K: v; ]  G# f
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic 公仔箱論壇" |. q$ {8 l" r3 u. o# Z% A
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
( ?" {2 Q' x8 w/ @9 x公仔箱論壇structures don’t last long and can be tough to come by.公仔箱論壇( [+ H, h! G3 \; y; O' c- @4 ~

& B( z8 E+ N( L' s公仔箱論壇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,bttvb; b9 H6 s! P$ W, ^+ h' N
show some of the biggest, oldest and most interesting impact craters on the planet.
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Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks 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。8 d9 _0 `& P7 x/ K
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million
# g: T5 r9 O8 T0 ?3 b0 wyears old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent 1 q5 C; z9 S. T: }; b" d
unidirectional wind. The image above was taken by astronauts in the International Space Station in July. " m6 {) }. b2 z1 O0 c  a4 s
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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, ^% y% P5 P8 a+ z公仔箱論壇The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 公仔箱論壇6 T+ z* g' n. [  W% v
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
( J1 I& V3 [9 E9 i: Tcould be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.os.tvboxnow.com) y6 L4 j* P; X! m. ]
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The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact 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。5 h* B  v$ Q9 C* M! l2 ]. R% x
around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around os.tvboxnow.com8 ?" D# s' E" l7 B! X. J
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
; s4 u* G) L+ e' Limpact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
reservoir and popular salmon fishing location.os.tvboxnow.com. }8 A9 L* ]/ }0 e
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This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was tvb now,tvbnow,bttvb3 L+ |4 ]8 W% p4 C; a
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy 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。9 N6 d5 R8 h( F2 B. I+ m
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood os.tvboxnow.com* r  F- z/ x' M+ p& A
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million / g& [+ |/ n; s6 c6 v" |
and 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
NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellitetvb now,tvbnow,bttvb' l; `5 X% k; W/ p! J0 u# b; [: p
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4 I) s* q1 R5 a! w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 公仔箱論壇; k/ L- p, Z" k6 j- b8 W" b
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding ) h- p2 l6 ]8 F1 @
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.& U0 w( k9 W6 y5 k

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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.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。; R( U/ q" p$ y4 r! P5 q5 u

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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
! [# m  T$ |0 ], k! R1.5 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
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
8 J9 ~# }( j. E2 @ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
# |* a9 Q) I, @6 \! F1 ?公仔箱論壇around 5 million years ago.tvb now,tvbnow,bttvb+ G; |5 y  x, W" S
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" X2 l' s" @, U( ]! _公仔箱論壇The Lonar crater in Maharashta, India is around 6,000 feet wide and 500 feet deep and contains a saltwater lake.
- X5 d  ~, |' MScientists 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.
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s os.tvboxnow.com6 w# h1 F! D; I- Z) \/ P7 v
Terra satellite. It is a simulated true-color image
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9 O3 o/ S7 E$ k# T9 K8 w公仔箱論壇The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
( S0 j/ d) R; ~( Uos.tvboxnow.comThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.tvb now,tvbnow,bttvb0 m  \/ d& C; p- B4 ^' k' m0 h
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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 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。' C0 G, Z; ?" i- h0 Q% z7 I
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.