What is the Chesed that He made the moon and stars to rule at night?
Radak: Their light is needed for people who travel in Midbaros or on the sea. They are needed for vegetation - "Geresh Yerachim" (Devarim 3:14). The moon has power also over water - "Ma'adanos Kimah Oh Moshchos Kesil Tefate'ach 1 " (Iyov 38:31). Also every star has power over vegetation, rocks or metals.
Malbim: Forest Chayos go out at night, and man rests. When the sun shines, the Chayos enter (their hiding places - 104:20, 22).
Radak and all the Meforshim explain this verse to discuss stars! In some editions, Radak does not bring this verse. Alternatively, perhaps the text should say 'Lahem' (them i.e. the stars) in place of 'la'Yare'ach' (PF).
