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。: T+ x; |9 Z3 D

( z, v# A6 s% xos.tvboxnow.comAsteroid impact craters are among the most interesting geological structures on any planet. Many other 3 @+ A# H9 J6 U5 K- j7 ?1 @
planets and moons in our solar system, including our own moon, are pock-marked with loads of craters.
; n/ m& ?  ~/ V4 F" P! O7 kBut because Earth has a protective atmosphere and is geologically active — with plate tectonics and volcanic tvb now,tvbnow,bttvb  w7 v0 ]4 E! l  Y  d% F8 m
eruptions, mostly relatively young oceanic crust, and harsh weathering from wind and water — impact os.tvboxnow.com, N, x8 S2 E) J8 \: j0 y2 j
structures don’t last long and can be tough to come by.tvb now,tvbnow,bttvb: K+ y$ \# F6 t3 ?) f
os.tvboxnow.com' G9 i* S. A- B; Y. N8 h( t
But on a few old pieces of continent, especially in arid deserts, the marks of asteroids have been preserved. , y+ |  m2 C8 r. P/ u
One well-known example is our own Barringer crater, also known as Meteor Crater, in Arizona. The images here os.tvboxnow.com) l8 A) y, {. y' y# T& I9 \
show some of the biggest, oldest and most interesting impact craters on the planet.
! i% ]) Y  d0 r' y5 @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。os.tvboxnow.com6 O; q" w, O" _% c9 f8 ^6 A
Aorounga crater, pictured above and below, is one of the best preserved impact craters on Earth, thanks ( f9 o/ U+ k  E1 x4 F4 `# k
in part to its location in the Sahara Desert in Chad. The 10 mile-wide crater is probably around 350 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。8 Z$ F) \; l0 c6 x
years old. The stripes are alternating rock ridges and sand layers, known as yardangs, caused by persistent 9 `: w( `! K4 q
unidirectional wind. The image above was taken by astronauts in the International Space Station in July. - R5 d# p' ^3 T" t  F
In the radar image below, taken from the space shuttle in 1994, reveals that Aorounga may be one of two or three craters.
' d$ D9 G! V/ X: `8 iTVBNOW 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。
2 O+ B. h, p6 T& _" H; k
: e4 I3 m, ?5 Y6 x( T; E4 H0 `公仔箱論壇tvb now,tvbnow,bttvb9 X5 a/ C5 ?& F2 \7 e0 e2 z2 X% b

; u- m+ C+ N7 \. S) q) K/ T/ c5 xos.tvboxnow.com
" u$ Y2 q2 e5 F) j# r" Eos.tvboxnow.comThe Shoemaker crater in Western Australia, formerly known as the Teague crater, was renamed in honor of the planetary
1 g- J: G$ _! V& w& Zgeologist Eugene Shoemaker for whom the Comet Shoemaker-Levy 9 is also named. The age of the crater unclear, but it   g& m1 }2 t1 B( y
could be 1.7 billion years old, which makes it the oldest known impact in Australia. The brightly colored splotches are
0 ?$ c  |4 Q- M  i9 j1 t: Jos.tvboxnow.comseasonal salt-water lakes. This image was taken by the Landsat 7 satellite./ R* ~- q$ a* a+ O3 @

5 e! Q! I' a5 A0 o9 a% P- a- ]" Fos.tvboxnow.com
$ o3 r/ k, R( H! z" K& C
% E! j3 u5 I) i' T2 C公仔箱論壇The Manicouagan Crater in northern Canada is one of the largest impact craters known on Earth. The impact occurred ! f% a  h0 G6 e1 o
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" K( k3 i3 c; {4 Q
60 percent of all species. Though the crater has mostly eroded, Lake Manicouagan outlines what is left of the 43-mile wide
8 i2 n7 Q0 z" D* {/ h. @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。impact structure. The asteroid that created the crater is thought to have been about three miles wide. Today the lake is a
' s1 v" ]. E8 d) X6 {: y4 e7 ~* hreservoir and popular salmon fishing location.
( p9 Q( K5 d2 Z( b6 D( `: T9 v" [7 S9 ITVBNOW 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 Q; H" G+ K4 Y5 g

$ \& V* b4 u6 H4 h) F2 D* ~9 |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。
( I4 M1 c/ h2 P. O6 _; M3 R+ i公仔箱論壇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  ?$ n& \: M; k7 t( D: |

1 [0 P* J- Y' x* U2 H, eos.tvboxnow.comThis crazy looking structure in Western Australia is called the Spider crater, for obvious reasons. Geologists determined it was 1 t; l& D5 ?: K" Y" x2 w
an impact crater when they found shatter cones, telltale cone-shaped, grooved rocks found only around impacts. The crazy 6 U+ r! H( J7 T( O" `& d6 n2 n
looking legs surrounding the impact are mostly due to erosion of different rock layers. The harder sandstone ridges withstood
$ O# T: I# k+ p7 a3 T; q3 fthe weathering of wind and water better than the softer intervening layers. The crater is somewhere between 600 million   i3 B! Q) D" A5 W( @2 e8 r
and 900 million years old and the raised area at its center is around 1,600 feet wide.os.tvboxnow.com$ [* @" k7 v1 V+ W- Y* h

2 f+ I- Q* l6 v- B$ p. c公仔箱論壇The image above is a false-color image taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on
/ J2 x, Q! c$ Gtvb now,tvbnow,bttvbNASA’s Terra. The true-color image below was captured by Taiwan’s Formost-2 satellite
3 u- L% v$ S# N/ V# ^) S
, O; `; K9 X0 O- x+ t" }7 Atvb now,tvbnow,bttvbtvb now,tvbnow,bttvb* R/ A. O+ |& ~2 X4 f- S) J1 O) U! K
  I, w% N: s" P- G
公仔箱論壇/ e# C0 c: O! X; C8 Z  ^# t- n3 q! y
) o$ W- K' v/ |; l* |; I
The Gosses Bluff crater in Australia’s Northern Territory sits between two mountain ranges. The raised circular feature in the
0 Y* l( v0 a2 ^8 n' D* FTVBNOW 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。center of the structure is around 2.8 miles across, but the original crater rim was probably at the edge of the surrounding
8 U( d- f3 a% ]4 f) u3 wgrayish area. The crater was formed caused by an asteroid impact around 140 million years ago.
3 C2 {# t2 p9 t. s  D- eos.tvboxnow.com
! |8 a* W( l* V, DTVBNOW 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。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。' j, c2 l/ r4 e

7 y( B9 Z* }4 ~2 V: D  i" F* @- WClearwater Lakes in Quebec, Canada were formed by a pair of asteroid impact craters. The impacts probably occurred os.tvboxnow.com( q7 Y" d0 k6 e
simultaneously around 290 million years ago. The larger crater measures 22 miles across.' U  O. u4 v" G& D; p
1 A: e& X* e8 [1 H" f0 k/ p& N5 R8 Z
  J' a0 g- p0 x6 D  L, A
# W" ^( ~1 w3 ?/ B% ~
The Roter Kamm crater in Namibia is hard to see in visible light, but shows up more clearly with imaging radar. The crater’s
% W/ ~' A& x& H8 WTVBNOW 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。1.5 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。; o8 |: V/ x# _' G* P8 H! N
the space shuttle. Irregular surfaces show up brightly and smooth areas are dark. The white splotch at the bottom of the
9 S: p$ {: G9 ntvb 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 ( y0 {. }$ B) @% D
ejected during the impact, the red is limestone outcrop and the green areas are mostly vegetation. The impact occurred
$ J% c# h9 u2 Y5 X+ {os.tvboxnow.comaround 5 million years ago.
, D* {) J$ D( p! g7 b  H- f公仔箱論壇4 G2 N5 D2 i7 g7 q
公仔箱論壇6 ~# B4 {2 N# ^  h- s4 A  _

5 C- R8 Q3 ?' i  r  p4 s" _& v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. ' \- E0 u) h( }% h% J
Scientists determined the structure was caused by an asteroid through clues such as the presence of maskelynite, 公仔箱論壇2 U; l1 E: E/ r0 X2 {  W0 S
a glass that is only formed by extremely high-velocity impacts. The impact occurred around 50,000 years ago.
  Q/ N# Y. f* T" `tvb now,tvbnow,bttvbThis image was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA’s
8 I5 |9 G- e$ f1 i公仔箱論壇Terra satellite. It is a simulated true-color image
1 E+ x9 C5 v+ H+ K9 }
( `9 X/ z; N4 }/ G5 {& gTVBNOW 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。os.tvboxnow.com: G4 n# n" P) q3 B

5 i& P2 }( l! ~; yTVBNOW 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 Vredefort Dome in South Africa is possibly the oldest and largest clearly visible asteroid impact on Earth. + e. l8 e' ?' j6 A* x0 G
The 155-mile crater is approximately 60 miles southwest of Johannesburg and was formed around 2 billion years ago.tvb now,tvbnow,bttvb- m- G% u, [. z
tvb now,tvbnow,bttvb& }. U# E: n' p- C
os.tvboxnow.com" Z/ T1 ^" [1 l2 c

! A( q* K2 p; x3 A; 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。
/ d. |! |4 |# }6 F4 y$ L公仔箱論壇
! {* I2 E0 X& _tvb now,tvbnow,bttvbArtist’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.com2 x" R) I) ~) @! o# ]
a 300-mile wide asteroid would look impacting Earth. This event probably would have killed everything on the planet.
8 x, _. m) l6 _9 ~3 o6 Q# sos.tvboxnow.comFortunately, NASA says nothing this big is headed our way anytime soon.