Taken Aback, Amazed, Horrified, Flabbergasted
noun, verbal noun
I look up to heaven, and I am taken aback and amazed by it. It's just so amazing.
ぎょうてん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
私は真美がどれだけ速くベーコンを食べれるのかってことにびっくり仰天しました。
I was astonished at how quickly Mami could eat bacon.