As a plane soars over the high desert of southern Peru, the dull pale sameness of the rocks and sand organize and change form. Distinct white lines gradually evolve from tan and rust-red. Strips of white crisscross a desert so dry that it rains less than an inch every year. The landscape changes as lines take shape to form simple geometric designs: trapezoids, straight lines, rectangles, triangles, and swirls. Some of the swirls and zigzags start to form more distinct shapes: a hummingbird, a spider, a monkey.

These are the renowned Nasca lines—subject of mystery for over 80 years. How were they formed? What purpose could they have served? Were aliens involved?

The lines are found in a region of