In edit mode select side faces and assign material with Emision Shader.
This glass plate consists from three materials:
front/back side with Glass Shader
bottom side with Emission Shader
top/left/right side with Glass Shader but now with Roughness 1
To make an object that receives no shading, just plug the color directly into the Material Output with no shader in between.
As you can see from the image, the black planet is surrounded by lights and an emission object (I put planes to show that there in fact lights there). You can see with bloom on, that there will still be some color bleed-over, but there ...