How to implement halo effect with Wpf 3D? -

i'm trying build 3d earth wpf viewport3d. have created earth , works pretty good. want add halo effect around earth attached image:

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some recommend use diffuse material globe model. build slight larger globe model emissive material , little opacity. effect not good. affects color of diffusion material this:

how can implement effect first screenshot?

i've done creating ring, inner radius same radius planet , outer radius relect atmospheric depth. oriented 'face me'. using texture coordinates lineargradientbrush have atmosphere fade sky blue transparent black.

alternatively, there pngs around of semi-transparent cloud layers use on larger sphere.