Oh, hah. I saw 行星 when I was looking up star stuff, but just took it for a variant transcription of 恆星 because 恆 and 行 sound the same in Cantonese. XD Not in Mandarin, I see! Well, at least now I know. And the "fixed star"/"wandering star" distinction makes sense (and also didn't occur to me, since I only really know 恆 from 永恆, so I think of it as permanence in time, and hadn't realized it also meant "fixed" in space).

Zhou Shen's second concert tour being titled "C-929星球", because he's canonically from another planet :P

Hah, I love it. Complete with 929 and all. :D