The AetherWebsite: https://www.curseforge.com/minecraft/mc-mods/the-aether/
One of the biggest projects in Minecraft Modding history. Five very well-known and talented modders have joined forces to develop the Aether, a celestial realm found in outer limits of the atmosphere. The Aether is what you could call the "antipole" of the Nether. The Nether is a network of desolate, fiery caverns filled with bloodstained Cobblestone and sticky Soulsand; it lies beneath the very soil of our Minecraft world. The Aether, on the other hand, is a collection of floating plains and islands, all connected together to create a breathtaking dimension of the skies. Even during the night, the Aether is still quite peaceful, and a normal day in the Aether is the equivalent of three days on the surface.
For Minecraft 1.2.5
Forge and Player API required