5.39.217.76- p" A @. X8 J* Z+ S/ p
: V! T0 Q' W3 W% d3 ]; r. ?' yAsteroid impact craters are among the most interesting geological structures on any planet. Many other
9 ]. V% x4 T8 G' H2 wplanets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
, ]& C2 h# |1 m- g9 w$ }公仔箱論壇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。( D/ ^$ y5 {9 P {' w$ X5 i
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact
- _+ X+ i* [% h: p2 ]structures don’t last long and can be tough to come by.公仔箱論壇- y* Z! d# ~7 g7 U
6 S0 c/ c: q' }4 I0 W
But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved.
' D7 M8 R7 C+ s3 o( U. _$ 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。One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here
& x# u( |) T+ [- Rshow some of the biggest, oldest and most interesting impact craters on the planet.
r8 N. h7 S5 K5.39.217.76
7 R/ Z. t, }5 `9 @/ h _$ htvb now,tvbnow,bttvbAorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks & p; M+ w* n5 p" k
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 million 5.39.217.765 J ~! ^* c* f: Z& _: W e
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent tvb now,tvbnow,bttvb! V1 p$ \8 H5 ?- F; V P' C
unidirectional wind. The image above was taken by astronauts in the International Space Station in July. 公仔箱論壇' v* U( ~% g6 f1 O& P9 G0 S% W
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% @" U0 k5 d$ ^8 S8 J7 I6 M
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。) W3 l( K1 ^: R) V, z
tvb now,tvbnow,bttvb, u' j0 m7 N" R; h2 G
$ [" c4 R7 v/ Y$ q9 Z- W8 k& Y8 Etvb now,tvbnow,bttvb
1 C! _: c' L* {. ?- p$ p( O
- f1 F8 ^5 K' n5 M3 T2 mtvb now,tvbnow,bttvbThe Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary 5.39.217.76+ F( g0 ^6 w3 R1 o
geologist 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。/ W7 R; B" \0 C' \7 |
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are - `+ g- |% E* d; [+ z
seasonal salt-water lakes. This image was taken by the Landsat 7 satellite.
: [+ ]% o8 w2 S( q8 S; \; b" q$ z9 D" z. R
公仔箱論壇% d% A3 |) m$ |* _% R
公仔箱論壇( F. v5 Z1 s4 O
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。8 {) ?' E1 f4 t5 A8 ]6 l8 }6 U
around 210 million years ago at the end of the Triassic period and may have caused a mass extinction that killed around
% U' o% ~6 D3 Q9 ?" T' k) y7 n60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide 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 l8 R$ O/ N1 {6 a2 T* t
impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
5 n V3 K [- j( v& wreservoir and popular salmon fishing location.
; x& F9 R( e5 L% |, F, d" H公仔箱論壇5.39.217.767 C8 P6 h4 z0 m( W Q0 x9 \
tvb now,tvbnow,bttvb! O; ~5 ?/ t) D* f( Z
0 M" j6 ?+ K7 {* ?9 ?公仔箱論壇 公仔箱論壇3 Y! J; g! R5 Q6 p* f
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。* n/ J! a6 k: ~4 [+ V
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。& z& e4 J0 Y' D0 ^( J4 U4 U4 K, E; @
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy tvb now,tvbnow,bttvb) N* Z7 v: }/ {! ]) T7 |; W
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood 公仔箱論壇6 \8 P; M& K9 X/ a
the weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million . V0 m3 X/ c& w
and 900 million years old and the raised area at its center is around 1,600 feet wide. ~6 G: r* |# W3 E4 n/ H }' E
1 |5 |: A3 J# \1 P3 I! m* x1 BTVBNOW 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。The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
- d, ]7 [/ T9 K7 c5.39.217.76NASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite
' @# w8 n( x' _, s公仔箱論壇4 B) {9 v; D- e9 q# T+ m. X6 Q
tvb now,tvbnow,bttvb/ ~, l$ }* o2 A
, `9 i7 o( F% T; T( e4 c" g: C
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 E/ f e1 g% O6 C+ |2 [
5.39.217.764 y/ j- O, y6 b8 G3 Q
The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the # d) b( o2 P% K e5 R
center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
. X4 B, b/ U2 S. a; q# R% d* d7 T5.39.217.76grayish area. The crater was formed caused by an asteroid impact around 140 million years ago.tvb now,tvbnow,bttvb2 m( D) H, ~3 U8 p0 U5 |5 Q. g0 m
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。' o6 n7 L8 _* p( p

, z% _7 C9 S# O6 `/ U- k) k, Ktvb now,tvbnow,bttvb+ u3 P2 u! a& b
Clearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred 公仔箱論壇7 c. [! D h: F! {& j) c, m7 t
simultaneously around 290 million years ago. The larger crater measures 22 miles across.公仔箱論壇/ L y: l' Q# }" ?2 q" s( l$ l
9 \$ G5 H# g& k+ t/ d" j$ I/ t
+ Z$ E" ~ C! L1 }9 r
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。4 [6 w) c$ S" H3 i4 b' Z" T4 ]
The Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s , K" P( [9 ]" v, S! J7 r5 n
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 boardTVBNOW 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$ r. h6 }$ g# x `* p
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
" ?, f' I. `, X Xtvb now,tvbnow,bttvbphoto is a rocky hill, the darkest areas are wind-blown sand dunes, the blue around the crater’s rim may be material that was
`. h8 {. J2 m! }' {% E7 hTVBNOW 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
4 N# F( t4 ?0 ~5 ]2 g$ K9 c5.39.217.76around 5 million years ago.; X2 [# x/ l1 a& V+ K3 m7 P3 x
公仔箱論壇. A( `, z3 _: F8 `5 ?

" e5 J5 p4 D& z/ A( @0 c# n6 Z; C公仔箱論壇
4 [ Z& ~* }) l# m/ O! z5 W, Y, sThe Lonar crater in Maharashta, India is around 6,000 feet wide and 500 feet deep and contains a saltwater lake. 公仔箱論壇. Q! P# b ~& t: ^3 M0 N7 B
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite,
1 B" q3 t0 j8 C8 X# _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 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。* f1 c5 c2 ?4 k f4 f) q. A
This image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s 5.39.217.763 c3 [3 O+ l% @; \9 l
Terra satellite. It is a simulated true-color image
- D2 Q; B4 o; V5 r, m; ~. e5.39.217.768 X$ r( Z- F5 G( y; g" F

* l2 u7 p- N- Q1 M! U7 ATVBNOW 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 N, f* D" m) I9 U. cThe Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth. " ?2 ^0 y& E. \/ a4 g
The 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.
( ]: @( o3 L' K$ x- c5.39.217.76公仔箱論壇 u6 ^& ~5 V, n1 V
5.39.217.76+ C w! l: |3 T. ~: G$ J
D- y$ [; ?# y3 f/ h7 E g& B

6 k5 s! j' w1 f' ]8 [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。/ `" d* A4 a' d" M/ q. J
Artist’s rendering of a space object or phenomenon, so we couldn’t resist this beauty. This is one man’s idea of what
3 o. n4 D1 z! [# o3 }; Ha 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
& e) t8 b' w7 b8 o/ sFortunately, NASA says nothing this big is headed our way anytime soon.
|