 Then that degree of darkness is reckoned as being true when the sun has fallen a certain number of degrees below the horizon (for example, 7°5′ below the horizon), and that becomes the actual standard used for all places and all dates.One calendar day ends, and the next day begins, during the evening.The Talmud states there is an uncertainty as to whether the day ends at sunset or nightfall, so the time in between has a status of doubt.