* Personification: The earth is given human qualities by being described as having an "edge." Earth is a sphere, not a flat surface with edges.
* Hyperbole: The statement is an exaggeration because the earth is a globe and doesn't have a literal edge that can be seen.
* Imagery: The sentence evokes a vivid mental picture of seeing the earth's edge, even though it's impossible.
This sentence likely uses these devices to create a sense of wonder or to emphasize a feeling of vastness.