How do I make a working shader that will make me a realistic enough atmosphere?

[Goosey]

This is my first time posting and I apologize if I might sound like an idiot somewhere, but I've been trying to make a space game with pretty good progress so far and I've wanted to make a shader for my atmosphere, but it doesn't do anything that I want it to do. The atmosphere is a circle and is just drawn at the position of the planet it is on and has the shader applied to it. The shader is meant to give off a nice fade, but it was acting really strange and never gave me the shade in the right place. I started off with just a basic fade, without having a point where it starts and ends. I had to ask an AI for help, but that was useless. I deeply, deeply apologize if my code is messy and looks like a bomb went off, but I will clean it up eventually.

[pgimeno]

I'm not sure if the effect you're after is understood. It's possible that the effect you are trying to do is possible to obtain without a shader.