For more detail this asset from the Unity Asset Store: Click Here
This is a paid asset, but we’ll share Simple Sun Shader for FREE, Please keep in mind this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Simple Sun Shader v1.2
❶ Shader has 3 variants: basic, dual color, and textured.
❷ Animates smoothly and looks great at any scale using a 256×256 noise texture, and you can reduce the size further without notably harming the appearance (even 32×32 works).
❸ Many parameters are exposed for tweaking and a script is included for easy access to properties and keywords.
❹ Suitable for low-end mobile devices. The showcase video was recorded on a Nexus 5 at 60 FPS.
❺ Renders using a single quad and can be used in particle systems.
You can download the showcase video in HD from here.
Praise the Sun.