Open up sphere and animate out

Hi everyone,

I'm looking for some pointers on how to animate a sphere open.

I have two hemispheres that have bevelled edges, giving the impression of a sphere split in half. I have one outer sphere around them that I would like to animate to reveal the split underneath (making it look like the outer sphere is actually breaking in half).

I need the outer sphere to sort of open up and rotate out, but I have absolutely no idea how to go about this. My Cinema knowledge is fairly limited, so I'd really appreciate some help.