ipas
<< i would like to create the effect of a planet exploding with the
explode ipas then the particles forming a vertex and swirling around
and finally forming a new planet >>
1) Create & render your explode sequence to disk.
2) Create your vortex sequence using Vortex 3D from Blackbox (I assume
you didn't mean 'vertex'), framed for a good match with the tail end
of the explode sequence, and render that sequence to disk.
3) Use a morphing program to dissolve/morph from the tail of the
explode sequence into the vortex sequence, and render that to disk.
Then reverse the order of the entire sequence, and append those
frames to the original sequence.