Highlighting areas of an object in contact with another?

Hey all. First time posting yet a long-time lurker on here.

No point in babbling, onto the question. I'm wondering how you would highlight on an object — a sphere for example — the areas that are touching other objects. To further the sphere example, let's assume there's a plane as well. So the sphere is placed a bit off center along the horizontal plane. What I'd want is for the outsides of the sphere to be highlighted, and given a special glow-y texture of some sort.

This has just been one little trouble I've had while I've been thinking through the next step for a small project I've been working on.

I appreciate any help, and if you need me to clarify my example (it made sense in my head!) feel free to ask.

Thanks much.