Celestial Resizer

Minecraft draws the sun and the moon as flat quads whose on-screen size is baked into the client as two plain numbers. A pack can ship a beautiful 512×512 sun.png, but the game still squeezes it onto the same small quad — so the sun never actually looks any bigger. There has never been a vanilla way to change that. This mod intercepts those two numbers and hands the decision to your resource pack. That is all it does.

vanilla (scale: 1.0)	"sun": { "scale": 2.5 }

With no pack installed the mod does nothing at all. Sizes stay exactly vanilla, so it is safe to ship alongside packs that do not use it.

Quick guide for authors of resourcepacks: click