Thumb for the question, thumb for the answer! As this rule sheet didn't ship with my copy of the game, I had no idea! This does make the Utopian planets much more valuable! Thanks to both of you for enlightening me!
This rules sheet was not prepared when the game shipped, as the Bonus planets were sort of added later, the rules for them were not in the rulebook. We actually have no printed versions of the Bonus Planet rules - only the online version. I linked a PNG file, but there's a PDF on BGG.