I changed like to as if because apparently there are people who will throw a hissy-cow if they see like used that way. Like isn’t wrong, though, so don’t feel you have to do the same.
I changed was to were because something large and metallic screaming isn’t an actual possibility. (You wouldn’t say I wish I was an alligator, because it is highly unlikely — impossible, even — that you could ever be an alligator. The correct form is I wish I were an alligator.)
I combined the next-to-last and last sentences because 1) there’s no reason to separate them where they are in the original version, and 2) the words flow better when these sentences are combined. A viable alternative is to have two sentences that are divided this way: It was loud, so loud. The people of Earth were scared.
(If you’re unspeakably paranoid about anything that could be mistaken — yes, mistaken — for passive voice, change that last word to afraid.)
Under any circumstances, the names of planets should be capitalized. The end of this example is talking about a planet, not dirt.
The sound was heard in cities all over the world, and it seemed to erupt from nowhere, as if something large and metallic were screaming. It was loud, so loud, and the people of Earth were scared.