* We haven't discovered them all: Our understanding of the solar system and the universe is constantly evolving. New moons are being discovered all the time.
* The definition of a "moon" is fuzzy: There's no universally agreed upon definition of what qualifies as a moon. Some objects might be too small, or their orbits might be too irregular to be considered true moons.
Here's what we know:
* Our Solar System: The eight major planets in our solar system have over 200 known moons, and more are likely to be found. Jupiter and Saturn have the most moons, with dozens each.
* Exoplanets: We've discovered thousands of planets outside our solar system (exoplanets). It's likely that many of these exoplanets have moons, but it's extremely difficult to detect them directly.
The bottom line is that the number of moons in space is likely to be vast and constantly growing as we continue to explore the cosmos.
