。
Why does the moon shine at night?
Literal
Why moon [topic-は] night shine [explanatory-の][question-か].
A reflective scientific question. どうして 'why' is somewhat less formal than なぜ. 夜 is used adverbially without any particle — a common pattern for time words like 今日 'today' and 明日 'tomorrow,' which attach directly to verbs (夜輝く 'shine at night'). The のか ending marks this as a pondered or rhetorical question, seeking explanation rather than a simple factual answer.