As you learn, she is on none of the three planets. However, after you have beaten all three, and have all three space knights with you, they will suggest you look for a giant asteroid that holds a legendary portal to another galaxy. The asteroid is in the asteroid belt, near x-11 Y-82, and if you go there you will find the Golden Key, the key that opens the portal to where the princess is being held.
She isn't on a planet.she is on a asteroid (if you are talking about astro-knights island)
With Mordred
Astro Knights
I think that it was Mordred.
The phoenix is on the jungle planet
The Princess has been captured before the start of the quest on Astro Knights island, and is not seen until the final battle in the lair of the Binary Bard.
she is on astro knights iland in space
the jungle planet is in space on astro knights island.
Green.
There are no cubes on Astro Knights island. There are ice floes on the Ice Planet, that you jump across to avoid the robot fish.
The Laser Lance.
No. Although there is a red planet, it is the Fire Planet and is not intended to be Mars.