Night One

"Why is she standing out there? What does she want?"

Night Two

"There's something off about her...."

Night Three

"That's not Fluttershy..."

When Apollo 11 lands on the moon, Neil Armstrong utters his famous lines as his boots land in the lunar regolith, but when he turns around he finds something no one was expecting or had ever planned for.
There's an alien on the moon. And it's blue, four-legged, and staring at him.

Sequel here.