Joel 2:10

The earth shall quake - the heavens shall tremble - Poetical expressions, to point out universal consternation and distress. The earth quaked to see itself deprived of its verdure; the heavens trembled to find themselves deprived of their light.

The sun and the moon shall be dark - Bochart relates that "their multitude is sometimes so immense as to obscure the heavens for the space of twelve miles!" - Ibid. p. 479.

The earth shall quake before them - "Not," says Jerome, "as though locusts or enemies had power to move the heavens or to shake the earth; but because, to those under trouble, for their exceeding terror, the heaven seems to fall and the earth to reel. But indeed, for the multitude of the locusts which cover the heavens, sun and moon shall be turned into darkness, and the stars shall withdraw their shining, while the cloud of locusts interrupts the light, and allows it not to reach the earth." Yet the mention of moon and stars rather suggests that something more is meant than the locusts, who, not flying by night except when they cross the sea, do not obscure either. Rather, as the next verse speaks of God's immediate, sensible, presence, this verse seems to pass from the image of the locusts to the full reality, and to say that heaven and earth should shake at the judgments of God, before He appeareth. Our Lord gives the same description of the forerunners of the Day of Judgment; "there shall be signs in the sun and in the moon and in the stars; and upon the earth distress of nations with perplexity; the sea and the waves roaring, people's hearts failing them for fear and for looking after those things which are coming on the earth, for the powers of heaven shall be shaken" Luke 21:25-26.

2:10 The earth - A divine hyperbole. But this also may have a reference to the great day.