If you think about it in Danganronpa there are 10 murders or more, each done by a different person. There are 8 planets (Pluto might be included in this au) So that means if you decide too continue you're forced too use the moons since there are over 200 moons.
NOOOOOOOO- AAAAA I love the whole idea of this Entire Executions Very Much!!!!!! It's Like- At first, We all know Moon was going to be executed right? But then during The Executions, It all seems like Moon Was Battling with himself to clarify his Decisions over Some Questions. During then, He somehow needs to reflect on what He thinks is gonna be and the Reality part of the Executions. Which is pretty great but also really bitter to see, Like some of the Questions still left him Untold and Is Impossible for him to answer because of The Experiences he'd been through While Killing Earth. And Oh no, Not to mention the Part where he sees His Planet Friends slowly dying one by one. In Conclusion, He does not know what to do nor what to think anymore, This entire battle was just him figting alone and feeling really guilty and Terrifying over all the things he had done , And I might have a theory that the time where he sees His Friends(Venus,Mars,Mercury,and The Earth) all dying one by one, Was reflecting on how he sees himself as the true Murderer on this Case, and even if at first he's still a bit Terrified to be Executed, he knows that it's for the best, Hecc, He might even been afraid he'll done the same mistake again. And at the ens He clearly forgot that Everybody's there watching him, The remaining surviving Planets all coming together to see the end for both The Earth and The Moon.