Is the sky darkest just before dawn?

According to a popular Israeli song, written and composed by Shalom Chanoch, “It’s always darkest just before the dawn.” But is this accurate? The answer is unequivocally no. The brightness of the night sky varies depending on the Moon’s appearance, as well as on artificial lighting on the ground. Without moonlight or light from artificial sources, the light produced from stars does not change at all during the night.

The zodiacal light is a weak light resulting from particles of interplanetary dust that is visible on very dark nights. It can be seen mainly in the western sky after sunset and in the eastern sky before sunrise, making the sky look a little brighter than the midnight sky. The difference is barely noticeable when viewed from an urban setting, where light pollution from street lights, house lights, billboards, etc., affects the sky’s brightness.

Rather, it is the Moon that particularly affects the brightness of the night sky. During the two weeks following a new moon, it can be seen after sunset – but not before sunrise. At such time, it is darker before dawn simply because the moon cannot be seen. After the middle of the lunar month, the moon will also be seen in the sky before sunrise, so that the hours just after sunset will be the darkest.

Therefore, believing it is darkest before dawn isn’t really based on anything. What can be said with certainty is that it is coldest before sunrise. This is because the Earth’s surface heats up during the day and then gradually cools during the night. Just before sunrise the ground has cooled for the longest period possible, so the temperature will then feel coldest compared to the beginning or middle of the night.