Dan, you're half the way with it, you've got the product, no company is so big they won't buy a good idea from a simple mortal, you have to make the second part of your effort, the one that is going to give you real money with it.
Don't be shy, just try and contact natgeo or the history channel, I'm pretty sure they would like to distribute an application like yours, as long as you show the earth destroyed by some mega space dissaster

. just go for it, you can't just end it here, maybe you've got a couple more years of work selling it, but it is worth giving it a try.
also Try Google
do it.
Regards