Take a walk on the beach. Pick up a handful of sand. How many grains are there?
Imagine, the total amount of grains of sand there are in the whole world, now double it. Double it again, and again. Double it again for good measure.
That might be close to the amount of planets. However, we won't know for certain until all planets have been discovered - and considering the problems involved, that won't be soon. If ever.
Probably, but impossible to tell as we are only just seeing planets within our own galaxy.
The planets we know of, some 300 now, are all in the Milky Way galaxy.
There are billions of planets and moons in the Star Wars galaxy.
It is not known. The Andromeda Galaxy contains about a trillion stars, many of which certainly have planets, though we don't know how many. Many of the planets likely have moons. All told, there are likely several hundred billion to several trillion moons in the Andromeda Galaxy.
nine
Planets orbit stars, stars orbit a galaxy. Planets are not "on" anything. A lot of stars out there have planets - we are just finding out how many now that we have better techniques to find them. So probably all galaxies have at least some stars with planets.
All of the ones we know about and have named are in our Galaxy.
All the planets in the galaxy have not yet been observed.
It is extremely likely, but we cannot yet find planets from that far away. All the planets we have found to date are in our own galaxy. The Andromeda galaxy is 2.5 million light years away whereas our galaxy is about 100,000 light years across.
The galaxy
The planets are part of the galaxy.
All the planets we know of... even those orbiting other stars... are in the Milky Way Galaxy.