He is the One who created the night and the day, and the sun and the moon, each swimming in an orbit.
Translation endnotes
[21:33] This verse clearly informs us that all (kul) celestial bodies rotate in an orbit. Interestingly, the earth's rotation around its axis is also implied by the expression "night and day." See 27:88; 36:40; 39:5; 68:1; 79:30.