Obsessive Astronomer

If it is night, and the active player of the previous turn cast two or more spells during their turn, it becomes day.

If a triggered ability triggers whenever day becomes night or night becomes day, it only triggers if it was already either day/night and becomes the other. It does not trigger when the game becomes day or night for the first time.

You may choose to discard no cards when the Obsessive Astronomer's triggered ability resolves.