|
- 积分
- 17983
- 威望
- 17983
- 包包
- 26159
|
 , b7 M' z$ a ]7 e2 r8 ~& N
The fireball that streaked across the skies above & W9 f# W* y4 {6 n: Y
Chelyabinsk in Russia on 15 February 2013 is providing astronomers with a wealth 6 @0 c d: O5 w# b r. I) Y
of information. Two papers in this issue present detailed reconstructions of the
, T( x4 y: F9 H+ }) jChelyabinsk event. From an analysis of videos, Ji?í Borovi?ka et al. determined
9 k# B3 _- e; a' X# F9 }the trajectory and velocity of the superbolide with high precision. Its orbit : f) M7 k5 q' P4 P7 p
was similar to that of the 2-kilometre-diameter asteroid 86039 (1999 NC43), - f) {/ x4 }# R# P% z2 u1 X
suggesting that the two bodies may be part of the same asteroid family. And they
3 L$ N8 l, _! d$ A1 Tshow that it broke into small pieces between the altitudes of 45 and 30
$ Z8 H$ A, N( u* Skilometres. In the companion paper, Peter Brown et al. analysed the damage / r6 e6 ?6 V7 [9 Q; H1 s! ?5 s
caused by the airburst which they estimate was equivalent in energy to the ' x3 Y% A: R4 J3 [8 z
detonation of 400 to 600 kilotons of TNT. They suggest that the number of
+ J. J& c! o. @) {& dimpactors with diameters of tens of metres was an order of magnitude higher than ' @2 N3 P* z6 b8 R# Y% H
current estimates, shifting much of the residual impact risk to these sizes. On
5 C, ?3 Z" u" V- Athe cover, a 3D simulation by Mark Boslough using CTH code on Sandia National
' V2 I5 w7 c# D8 }Laboratories' Red Sky supercomputer, rendered by Brad Carvey using Houdini FX
. q' G" {" A/ n9 k# mand LightWave; background photo by Olga Kluglova, go.nature.com/wxuV58.
, R9 E9 Z: L. j/ M% K/ T3 E
w; a, A0 K% N2 e& F& \& Y |
-
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
