During the last two episodes of Book 2 and the last episode of Book 3 (both from the first Avatar series), we can see Aang in some sort of space-like universe where he's basically walking to someone who looks alike him but bigger and sort-of looking angry. You can read about it and see images here: http://avatar.wikia.com/wiki/Aang#Avatar_Spirit
The whole thing with Raava and Vaatu wasn't explained, nor mentioned 'till the Korra series. I was hoping you guys could explain to me what we're actually looking at in those scenes I mentioned, and if there can be made any references to the Avatar Spirit stuff worked out and explained in the Korra series. For example, is that bigger self Aang is walking to actually Raava?
Thanks in advance ^^