When you have beaten all three planets and have all 3 knights with you, travel to the giant asteroid at X-11 Y-84 in the asteroid belt. There you can pull out the Golden Key and enter the realm of the Binary Bard.
No, because you need the three knights to go with you. (see related question)
When you have all three knights with you, they suggest you look for a giant asteroid, which happens to be at X-11 Y-82 in the Asteroid Belt.
Once you have beaten all three planets and have all three knights with you, travel to the secret asteroid in the Asteroid Belt (down and left in the solar system). The asteroid is at X-11 Y-84.
The windmill is at the far right side of the island. There are three areas : the Village, the Castle, and the Mill.
If you mean the ones that the Queen gives you from Astro-Knights they are the planets at which the three knights are at.
As you defeat the three planets (jungle, ice, fire), the knights come along with you. So you have to beat all three planets to get all three knights. When you have them, go to the giant asteroid in the asteroid belt, near X-11 Y-84.
really all you have to do is read them they should help a little bit the island
If you are talking about Astro-Knights the four chosen ones are you and the three knights.
The three knights tell of a mysterious planetoid in the asteroid belt, where a portal to another galaxy exists. Travel to the asteroid belt and to X-11 Y-82, where you can pull the Golden Key and find the Princess.
When you have all three knights but can't find the Princess, the knights suggest you look for a fabled "giant asteroid". There is one in the Asteroid Belt near X-11, Y-82.
The three knights (Cador, Gawain, and Peleas) are named for knights from the legends of King Arthur. This is also the source of the names Mordred, the owl Merlin, and the kingdom of Arturus.
To draw the sword from the crystal stone, you must have defeated all three planets (jungle, ice, and fire) and have all three knights with you. (see the related questions)