Is the sky darkest just before dawn?

May 9, 2017
5 min
האמונה העממית גורסת שהחושך עמוק במיוחד לפני עלות השחר. ובמציאות: תלוי בעיקר במצב הירח ובאורות העיר

It’s always most dark before the rise of dawn” sang Shalom Chanoch in the song “Walking against the Wind,” for which he both wrote the lyrics and composed the music. Is this accurate? Unequivocally, the answer is no. The brightness of the night sky varies depending on the appearance of the moon as well as 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.

On very dark nights one can see the zodiacal lights, resulting from particles of dust in the space between the planets. This is a weak light that can be seen mainly in the western sky after sunset and in the eastern sky before sunrise. This light makes the sky look a little brighter than the midnight sky. The difference is barely noticeable when viewed from an urban setting where artificial lights (street lights, house lights, billboards, etc.) are affecting the brightness of the sky.

It is the moon’s appearance that particularly affects the brightness of the sky. In 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 one cannot see the moon. For the remainder of that moon, after the middle of the Hebrew month, the moon will be 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 for sure 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 the middle of the night.