http://free-zero.yi.org/lightball_anim5_1380145034.mkv example use of https://gist.github.com/ze-/6707422

lightball_anim5.pov

#version 3.7;
#declare inverse_n = function(n,x,y,z) { 1/pow(n, sqrt((x*x)+(y*y)+(z*z))) }
global_settings {
 assumed_gamma 1.0
 ambient_light 0
}
background { color rgb 0 }
camera {
 location <0,0,-13>
 look_at <0,0,0>
// right (16/9)*x // for widescreen image
 right 1*x // for square image
}

sphere {
 <0,0,0>,20
 hollow
 texture {
   pigment { color rgb 1 transmit 1 }
   finish { ambient 0 diffuse 0 }
 }
 interior {
   media {
     intervals 14
     ratio 0.0
     absorption 0
     emission srgb<0.37,0.65,1>
     density {
       function { inverse_n(3,x,y,z) }
       density_map { [0 rgb 0] [0.5 rgb 1 ] }
       warp { turbulence 0.9 hyper <sin(2*pi*clock),-1*cos(2*pi*clock)> }
       scale 0.7
     }
   }
 }
}