hai diyaaa!! oh gosh that is a tough question, im really no an expert on those sjhdbcjhsb i'll limit myself to planets + sun, moon and stars because i do not know much about astronomy so bear with me.

felix - sun. duh. obviously.
i know theres war between hyunlix and chanlix shippers for who is the moon but... for me the moon will always be chan (with or without felix lol) because of how nocturnal he is, but also i look for the moon for comfort sometimes and she feels as home-y as he does so: chan - moon
and basically thats when i start bullshitting, feel free to correct me on any of those honestly sdjhbcjs:
if we base the other 3racha members off of chan's, jisung would be the stars and changbin would be the earth methinks
hyunjin: mars simply because i think red really is his colour sjhdbchjs but i also thought of venus for him for some reason
seungmin: mercury, something about it being very similar to the moon...
minho: saturn, the jewel of the solar system :D
jeongin: neptune, maybe? i cant really explain why

again i barely know anything about astronomy so if you dont agree with me its okay, im not really convinced by my choices either but i wanted to give it a try!