What is a moon jump?

A Moon jump is a cheat code which allows you to hold the jump button and not fall down and release to fall you can stop high falls by pressing b near the ground .Also,to get Luigi go to big boos haunt (The Ghost House) as Mario and if you did not do this yet,complete star 1 by killing all boos then a boss boo,now go to one of the doors in the floor above the ones at the bottom and go through one (I do not remember, but there is one with a red box,if it's clear then go to the castle and stand on the carpet and then look up you will be flying,hit the red button and fall down.)hit the red block float up the place and go through a hidden door and jump in the luigi painting.
Ok,Kill the Boo in there and go through the door with the red coin and run fast through a falling bridge and turn left.enter the door and jump on the platform in front of you and then jump on the platform to your right (Do this quickly,the platforms are not stable!They will fall in a split second!).You should now be in a room with green checked platforms. Jump on the one right in from of you.It will travel to the right.When it get to the platform to the right then the left. Get off at the platform to the left. Run across the falling bridge. GO left and there is another checked platform. Get on it and when it comes to the one next to it, hop onto that one and repeat the process. When you get to the hole st the top, jump into it. Run up to the mirror and look straight into it. King Boo will give a short speech and then you battle him. Use the reflection of the mirror to kill him. Then go free Luigi!!!! I hope I helped!