Matthew Poole and continuators on Job 25:5

5. Behold even to the moon, and it shineth not . yea, the stars are not pure in his sight .

The Moon, though a bright and glorious Creature, Iob 31. 26. Cant. 6. 10. if compared with the splendour of the Divine Majesty, is but as a dark and earthy lump, without any lustre or glory. He names the Moon and the Stars, rather than the Sun, because they many times are eclipsed or disappear even to our Eyes, which is a plain evidence of their utter obscurity in respect of God's Light: whereas the Sun, though that also be obscure, if compared with God, yet it casts a constant and most clear light. Or by naming the Moon, and thence proceeding to the Stars, the Sun is included between them.

He can discern many spots and blemishes in them which we cannot see; and in like manner he can discover those corruptions or sins in us which are unknown to our own Consciences, which should make thee, O Iob, tremble to appear before his Tribunal.