My mind instantly answered that with "bright", which is what you get when you combine the sun and moon radicals to make 明(https://en.wiktionary.org/wiki/%E6%98%8E)
Anyway, that question is not without reasonable answers. "Full Moon" might make sense too. No obvious deterministic answer, though, naturally.
Edit: Spoiler -
It's 'Eclipse'
Eclipse, obviously.
https://neal.fun/infinite-craft/
For the record, Sun+Moon is indeed eclipse.
i just looked up mass of sun vs mass of moon (they differ by 10^30 vs 10^20), and the elemental composition of the sun: the moon would entirely disappear into the insignificant digits of trace elements which are in the range of .01 % of the sun. I could be off by orders of magnitude all over the place and it would still disappear.
Still think it was a good response :)
I'll just add that if you think this advice applies to you, it's the - https://en.wikipedia.org/wiki/Barnum_effect
It’s a reasonable Tarot question.
"Monsoon," says ChatGPT.