Asteroid Impact Craters on Earth as Seen From Space

; c1 @) ?/ B. o: _# {! z5.39.217.77tvb now,tvbnow,bttvb/ g/ q) ?! x* |( e: K
Asteroid impact craters are among the most interesting geological structures on any planet. Many other 5.39.217.772 O0 b2 Q5 `! a; F2 i1 v" l
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
But because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic 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。( F( ]1 o. ^, }+ l$ Z! Z
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
; @6 ~+ h* W, K) N. n! f, e: _# kstructures don’t last long and can be tough to come by.
& |7 W7 R. j) }tvb now,tvbnow,bttvbTVBNOW 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。* i, v5 N2 `0 c8 ~
But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
% m/ R, N8 J7 i0 Y2 f5.39.217.77One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here 公仔箱論壇$ s9 _- Q! T$ o9 H; p
show some of the biggest, oldest and most interesting impact craters on the planet.
( [3 |7 I( D; O; l
Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks
8 {+ j- r3 S" v9 O8 E- {0 gin 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& u$ I& d: @, G+ L
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent
2 C( P" k' L$ I% [公仔箱論壇unidirectional wind. The image above was taken by astronauts in the International Space Station in July. + [; H; V5 E+ Q9 G
In the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.
8 D. d' k) a+ Y3 H. t3 t公仔箱論壇

8 A& D1 I" o4 D/ p1 V8 y6 ?5.39.217.775.39.217.77& k* ~2 `" \5 }' r+ R. t
The Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 公仔箱論壇! T8 D8 q, X; |( ^3 c3 P
geologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
+ ^% c" v4 `5 Etvb now,tvbnow,bttvbseasonal salt-water lakes. This image was taken by the Landsat 7 satellite.5.39.217.77  x; h) H1 I$ c+ y! [
5 A4 l. Z. A. R; y  M4 z* d' G
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。! [' ^! y1 N  ^/ u2 }+ N7 Q7 l6 ~

( k0 n+ H3 H& u5.39.217.77The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred
& i5 f* x. H' |公仔箱論壇around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around tvb now,tvbnow,bttvb; R0 h$ j) i* W. R
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
8 r! h  j* Y' R: g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 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。: U! b8 w3 k  K8 ~5 O
reservoir and popular salmon fishing location.5.39.217.77+ I1 x( H, k- t, |: F
5.39.217.77; R7 y' I' w5 ]1 E

1 |: P, D/ P/ w3 ^tvb now,tvbnow,bttvb
/ ^/ A5 V8 ?! O* e. R+ H5.39.217.77This crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was
" w- f( ~/ l6 u1 i% J+ Q* Fan 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   B6 O8 P- O: |7 F) l9 ^
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million 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 j# T: `8 X; \+ `3 U
and 900 million years old and the raised area at its center is around 1,600 feet wide.
7 [$ ~4 [' I5 \! N
The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
, S( m( f6 O7 J3 @: `NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite公仔箱論壇* b) r9 \. E) _! j6 a8 J
5.39.217.775 Y5 g( k1 U0 W% q$ E" H
tvb now,tvbnow,bttvb4 w* t  v0 T6 X5 X5 E

$ p# A. b1 Z0 M) \! B# n5.39.217.77The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
& u/ t' v! a$ h* Z" r. U公仔箱論壇center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding . j% M$ K1 r' b5 A! v9 M; l# Z# T4 s
grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.- ]* q8 b" H, C9 o* w

. F3 Y: k2 C% x2 u0 v公仔箱論壇/ z9 B. F2 z" E# G3 c' P. j

- N9 ^3 U0 c* _% C) xClearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred
3 ^7 E2 m! r$ I' _tvb now,tvbnow,bttvbsimultaneously around 290 million years ago. The larger crater measures 22 miles across.
6 G1 j1 k' \$ C4 \* m6 }5.39.217.77  `3 Z* p0 n7 u0 i( F  v

, S- t* h0 D) C' {; ^公仔箱論壇; a) p+ p  J; L( A/ m
The Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s
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 boardtvb now,tvbnow,bttvb3 y8 K1 _1 n4 K3 v+ F+ p
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 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 x- ^5 U* s& O* z; D
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
, F1 r1 t& P6 b$ j$ M$ g5.39.217.77around 5 million years ago.

公仔箱論壇% l- I/ \+ j# ]9 Z/ k
+ R9 m1 L8 Y! N: J7 e- x
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。$ a( o7 d: T. f8 |
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
. y1 l& v  b# [a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago. 4 l5 F- F5 j2 h+ X$ U
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s tvb now,tvbnow,bttvb* ~5 e) w5 I+ f0 F
Terra satellite. It is a simulated true-color image
tvb now,tvbnow,bttvb9 v% f0 [/ x5 d. R6 {0 g- L

# J; v6 p1 q9 n2 \
1 q  _  C: R* Z( \) i8 }The Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth.
+ k8 b- C7 S, [( xThe 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.

# d5 g4 Q8 j4 J) v3 D5 S5.39.217.77公仔箱論壇2 {2 Q9 F8 H2 d% C

. C1 g; ]: g0 R. k5 O% d公仔箱論壇3 _' o; ^3 O) j( O. |0 l. g1 L4 I
( \: _; b( F0 [) K2 G
Artist’s rendering of a space object or phenomenon, so we couldn’t resist this beauty. This is one man’s idea of what tvb now,tvbnow,bttvb' G5 Z# Y) `  B
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
! N! F1 e) m6 @5 ~# h% C5.39.217.77Fortunately, NASA says nothing this big is headed our way anytime soon.