。
Dawn is just about to break.
Literal
Night [subj-が] just open-[volitional-よう]-doing.
Combines the imminence pattern ~ようとしている ('be about to X') with the intensifier ちょうど ('exactly, just'). ちょうど modifies the 'about to' nuance, emphasizing precise imminence — dawn is right at the edge of breaking.