iPhoto has disappeared from my Mac

So I just realized that the iPhoto application is completely gone from my computer and is nowhere to be found. I never deleted it, I literally just noticed that one day it wasn't there. As a result all of those photos are gone. I have a time machine backup from December 5th, 2014 (so about 5 months ago) and it says that I had iPhoto on my computer at that time. So for some reason in between those 5 months iPhoto disappeared. What could have happened?

Also, when I go to my December 5th backup I have no idea where I can find the iPhoto library that contains all my photos I had up until December 5th. Where do I find the iPhoto library through Finder?