Answer:
the sentence needs a punctuation mark
Explanation:
The sentence is made up of two clauses "Appearing almost like an alien planet," and "Edgar could see a huge grid of wind turbine in uniform rows and columns that stretched across the desert and the horizon." The second portion needs a period (or full stop). A period signifies where a sentence ends. Without a period, readers will be confused as they do not know where the sentence ends.
What ideas? Is there a picture?
No, that is not an onomatopoeia. That's more personification. Onomatopoeias are usually the sound the object makes. For example, "buzz!" is an onomatopoeia of a bee or a bug. You could phrase your sentence like this instead: "Crash!! The meteoroids slammed against the earth's surface." In this sentence, "crash!" would be the onomatopoeia.