* Our Solar System: Our solar system has 8 planets.

* Milky Way Galaxy: The Milky Way galaxy is HUGE and contains billions of stars. Each star is likely to have its own planetary system, but we haven't discovered them all yet.

* Exoplanets: Scientists have discovered thousands of planets orbiting stars outside our solar system (called exoplanets). This number is constantly increasing as we develop better telescopes and techniques.

So, the short answer is we don't know how many planets are in the Milky Way galaxy. We're still exploring and discovering new ones all the time!