2013年11月14日 Nature

nero1981

0 H2 \. F( B0 N/ R0 k/ T8 H% FThe fireball that streaked across the skies above
' J. _. W1 a1 M% [2 iChelyabinsk in Russia on 15 February 2013 is providing astronomers with a wealth
/ o4 `" U8 t2 a% E4 C: m$ sof information. Two papers in this issue present detailed reconstructions of the
9 k" [% A# u5 oChelyabinsk event. From an analysis of videos, Ji?í Borovi?ka et al. determined 1 A5 b/ e/ z- J, p3 ~2 R$ i
the trajectory and velocity of the superbolide with high precision. Its orbit
6 _+ j- o/ @8 x7 y4 {7 Y3 F; Xwas similar to that of the 2-kilometre-diameter asteroid 86039 (1999 NC43),
# L0 J4 m! v6 q4 `) H8 Osuggesting that the two bodies may be part of the same asteroid family. And they
! ]- Z* M, T. E; M& g/ `show that it broke into small pieces between the altitudes of 45 and 30 9 {1 r* e9 T! b9 {
kilometres. In the companion paper, Peter Brown et al. analysed the damage
6 o0 ~! U0 o% ?2 F% W( q# |caused by the airburst which they estimate was equivalent in energy to the
2 K: ^# Y& I6 @& m: U. Pdetonation of 400 to 600 kilotons of TNT. They suggest that the number of 5 v. @: O, a8 S1 @/ q
impactors with diameters of tens of metres was an order of magnitude higher than
8 g. ?6 v/ O% _& b4 {3 Bcurrent estimates, shifting much of the residual impact risk to these sizes. On
+ `4 ~2 V: O4 bthe cover, a 3D simulation by Mark Boslough using CTH code on Sandia National
  I5 _# z; Q) i& zLaboratories' Red Sky supercomputer, rendered by Brad Carvey using Houdini FX
( j7 _. s% L4 b' u3 Yand LightWave; background photo by Olga Kluglova, go.nature.com/wxuV58.
/ ?$ J- ~8 U- @  {- X9 b0 p+ N
  _% ~3 Y7 P1 G$ z7 e

游客，如果你要查看本帖隐藏内容请回复