Be astonished, O ye heavens, at this, and be horribly afraid, be ye very desolate, saith the LORD.
Be astonished, O ye heavens - impassioned personification (Isaiah 1:2).
Horribly afraid - rather, 'be horrified.'
Be ... very desolate - rather, 'be exceedingly aghast' at the monstrous spectacle [chaarab] - literally, go be dried up, or devastated: places devastated have such an unsightly look (Maurer.)