|
- 积分
- 17983
- 威望
- 17983
- 包包
- 26159
|
 ' o: d" v$ ~" ]' E4 ]
The fireball that streaked across the skies above
2 k; q4 N, a/ |% _Chelyabinsk in Russia on 15 February 2013 is providing astronomers with a wealth : h& ]4 _ @ N
of information. Two papers in this issue present detailed reconstructions of the % R6 B4 V+ G- ]* `& x# U
Chelyabinsk event. From an analysis of videos, Ji?í Borovi?ka et al. determined
0 u+ t4 D5 Z+ Sthe trajectory and velocity of the superbolide with high precision. Its orbit
1 _8 S0 X9 q2 r3 P' l! F- @was similar to that of the 2-kilometre-diameter asteroid 86039 (1999 NC43),
( u" Z2 o% }3 z# R. H) Gsuggesting that the two bodies may be part of the same asteroid family. And they
( N9 n2 y2 W) z& E8 e9 Ishow that it broke into small pieces between the altitudes of 45 and 30 $ o( H9 @0 R3 p& o0 ?* D% ~
kilometres. In the companion paper, Peter Brown et al. analysed the damage
' h0 l* M1 k' k* kcaused by the airburst which they estimate was equivalent in energy to the
+ S9 {! M' A0 \& {* u i* Rdetonation of 400 to 600 kilotons of TNT. They suggest that the number of 1 h; K# {9 |! D4 n9 R$ k
impactors with diameters of tens of metres was an order of magnitude higher than 1 i8 l0 d; K* u8 I0 Q1 C) c5 t6 U
current estimates, shifting much of the residual impact risk to these sizes. On
; w4 y, ? p3 q2 j1 M/ ~+ Hthe cover, a 3D simulation by Mark Boslough using CTH code on Sandia National $ H, n1 ^* z8 g6 F0 n
Laboratories' Red Sky supercomputer, rendered by Brad Carvey using Houdini FX - Y# y/ O3 q9 F" Z+ r3 r7 b
and LightWave; background photo by Olga Kluglova, go.nature.com/wxuV58.
9 C( q: p, O1 |, c6 `; T# S# o1 y( R
|
-
总评分: 威望 + 20
包包 + 20
查看全部评分
|
发表于 2013-11-17 23:43
发表于 2013-11-18 08:19
