I dont know about you, but I think auroras would be a beautiful and fantastic addition to the game. An aurora would happen in rare chances, only at snowy biomes and at night. This aurora would light up the sky, giving a 5% extra illumination. Another neat suggestion for the aurora to give it more quality, is that all mobs become passive when it happens. Endermen don't kill you for staring at them, creepers don't explode on you. (Unless you harm them)
Like I said, just an idea, but I strongly suggest the addition of it, for it will give minecraft a beautiful little addition.
I like this idea....of course Auroras if I am correct is just the radiation of the sun bouncing off of the earth's protective atmosphere so we would have to say that the Minecraft world (Still to new to know the name that is generally accepted.) is the same distance away from the sun and Earth which is possible so I believe that Auroras would not just be a good idea for looks but also for the astronomy outlook of Minecraft.