Let's say you're an alien life form who is seeing planet Earth for the first time from a vantage point of about 440 miles from its surface. You'd see great bodies of water, mountains, forests and deserts. But dotted throughout this foreign landscape, almost like tiny pock marks, you'd see something else: Telltale signs that some other force is at work.
That "force" is, of course, mankind. Humans have collectively reshaped the planet, leaving behind landscapes that stand in contrast to their natural surroundings.
Here, we've collected a handful of those blemishes, captured by NASA's Landsat orbiters, to give you a sense of what might catch an extraterrestrial visitor's eye.
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