go to the secret door
you go inside, get the moldy cheese and pull the lever down.
The only place is in the castle dungeon, below the library. (see related question)
Use the cheese from the dungeon (under the library in the castle). (*To get to the dungeon, see the related question.)
To see the solar system on Astro Knights island, go to the Planetarium. (not part of the game, but an interesting view)
next to a bookshelf.
To obtain the moldy cheese in Astro-Knights on Poptropica, you need to first find the rats in the secret dungeon. They will steal the moldy cheese from you, which you can then retrieve by using the Rat Trap item in your inventory.
In the palace the right door
IS IN DA LIBRARY... SOMWEAR.... and i dongt
You don't need to.
The only things you do in the castle dungeon (under the library) are pick up the cheese and throw the switch. (see related question)
After you get the cheese you put it in the princesses dressing room and capture the mouse to feed it to the owl.
The moldy cheese is in the castle library entrance to the castle dungeon. Get the gold coin from the fountain, pay your admission to the museum, and get the Library Slip. Now when you go to the castle library, you can click the shelf (McM) that opens the stairway to the dungeon.