not sure this will work but there is spray on glass frost at craft stores

Grease the roof? No, I would try what Solar Texas said. Call a local skylight company and ask if the dome can be replaced.

Thanks to all of you.

We had a peeping tom on the roof a few years ago

Story, please. Sounds interesting.

Grease the roof?

Hey, you're joking, but I have a similar story from my classroom: A couple years ago I had a handful of senior boys who thought it was hilarious -- in the last class of the day -- to rush to the door, stand in line, and jump up to grab the door frame and each do a dozen pull ups while exiting the classroom. The group'd enthusiastically count as each one completed his exercise, then they'd run down the hall hooting and hollering. Of course, their little game each day "trapped" 20 or so other students in the room while they played ... and some of those students were hurrying to catch the bus.

I talked to them and told them to quit -- nope. I wrote them up -- nope. They continued their little game. They knew they were being jerks, but they didn't care.

Here's how I fixed it: I brought a tub of Vaseline from home and liberally greased the top of the door jam. The end of the day arrived, and the first boy in line jumped up ... and quickly fell on his butt. That was the end of that game, and everyone else in the class was thrilled.