The moon is often considered to be female. This is the way people write about the moon in a poetic way. The sun however is considered to be a male. John

To my knowledge this dates back to grammar rules in old English. The generalization that I made for myself is this one: whatever that bears something can be referred as a female entity in English literature like she/her for bus or ship. In your sentence night is something that bears mysteries and things in itself, when it comes to descriptive language of literature you can say she/her, if not you can say it. Like the one I did earlier in my answer