you need a cloud flower.you need to have 2 or 3 cloud friends.
You get every green star.
you have to get every star, green star, prankster comet and comet medal
It's a hidden star and can be found by simply going to any level
the trial galaxy rock is on top of the observatory (or around it). you have to get the three green power stars and a green launch star will appear use it to get to the trial galaxy rock.
To get green stars, you go through each level and look for green stars. You can also listen for the star "sound."
you can find the green stars in the dusty dune galaxy), in the battle rock galaxy,(with luigi), and in the buoy base galaxy. You buy the planet for the dusty dune star, You find luigi under the battle rock galaxy(under where the normal star is) And you use a bullet bill in the buoy base to open the pipe underwater. Hope this helps!
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It is the trial galaxy. You need to get 3 green stars. 1. In a dusty dune level. secret pyramid. need to feed star. 2. buble breeze galaxy the pipe. 3. after unlocking luigi, he finds a star. Get his letter.
You have to first get all the normal/grand stars (no help from rosalina or your gonna have to do that level again to get the normal star, not the bronze star) before unlocking the green stars.
You go to the Trial Galaxies and talk to the green star.
1.when you kill the hammer bros and get the flower you fly around the corner to the right and get the green star. 2.when you first get Yoshi go to the platform in the middle and flutterjump to the green star in the distance.if you don't make it when Yoshi stops backflip off him.
when you get to the galaxy listen carefully when you hear a beatiful tinking sound use the camera and see if you find it.