A few hours later, we were having dinner with my mother-in-law and NJhusband asked her about the solar light in the planter. She had no idea what we were talking about! She didn't put it there either! We all went out to the front stoop to look at it. By this time, it was dark enough that it had lit up and the light was orange. I know from walking the dog, that our neighbors around the corner have orange lights, so I assumed it was one of theirs, though I still have NO idea how it got to our house. I asked NJhusband to go over to the neighbors in the daylight and see if he could figure out where it had been taken from their yard and put it back.
The next morning he takes the light back to its (maybe) home, but he can't figure out where it came from, so he leaves it on their porch....in their planter. Leaving them with their own solar light in the planter mystery to solve.
I'll let you know if it migrates back to our house.