|
- 积分
- 17983
- 威望
- 17983
- 包包
- 26159
|
+ d) m. ^4 t( Y8 }& d5 P9 J* D: z. BThe fireball that streaked across the skies above ' \/ y; U$ Y/ Y" d3 Z
Chelyabinsk in Russia on 15 February 2013 is providing astronomers with a wealth
8 a! `: Z3 X; `) sof information. Two papers in this issue present detailed reconstructions of the % L3 @) h8 Z& N" s. F! z
Chelyabinsk event. From an analysis of videos, Ji?í Borovi?ka et al. determined
& K& D* h5 P5 `9 C, `% Ythe trajectory and velocity of the superbolide with high precision. Its orbit . N, `/ k; b, ~5 k/ \0 Q: N
was similar to that of the 2-kilometre-diameter asteroid 86039 (1999 NC43),
- q8 s7 d5 \7 e' rsuggesting that the two bodies may be part of the same asteroid family. And they 0 `3 C* e( d. Q5 i
show that it broke into small pieces between the altitudes of 45 and 30 : m& f2 B9 Q( R1 G# R; L% e: \
kilometres. In the companion paper, Peter Brown et al. analysed the damage
% c+ D0 K- V; x8 q6 W: i/ U8 j2 ]4 P& Pcaused by the airburst which they estimate was equivalent in energy to the
+ w) f7 O7 h0 V; ?detonation of 400 to 600 kilotons of TNT. They suggest that the number of - H% I/ y. K/ Y' j3 u. S
impactors with diameters of tens of metres was an order of magnitude higher than
7 ]) S( ^: q9 B. J6 c; F& ocurrent estimates, shifting much of the residual impact risk to these sizes. On
" ~+ p/ j; F: ?' ~% e7 Lthe cover, a 3D simulation by Mark Boslough using CTH code on Sandia National 8 G3 g$ i& w( ?/ @1 S
Laboratories' Red Sky supercomputer, rendered by Brad Carvey using Houdini FX
# C! _# P8 m( H" wand LightWave; background photo by Olga Kluglova, go.nature.com/wxuV58.
3 L5 a; E2 m1 z& y# ?0 ]
2 f) G* m5 [6 | |
-
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
