1)
How could Moshe "raise his hand upon the heavens"?
1.
Rashi #1: The words "Al ha'Shamayim" mean (not 'upon the heavens' but) "towards the heavens."
2.
Rashi #2 (citing the Midrash): Hashem raised Moshe above the heavens. 1
1
Sifsei Chachamim: Thereby empowering him to bring the next three Makos, which took place in the atmosphere. Refer to 7:14:8:2, 7:26:1:2**, and 9:14:1:2.
