system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible for a moon to also have its own moon?
gpt
It is possible for a moon to have it's own satellite, yes.  Whether it would be classified as a "moon" or not would be up to the academics, but a loose definition is:

* A distinct, whole object
* A solid object
* In orbit around a more massive body

The mass of the satellite orbiting a moon would most likely be very small in relation to that moon.