Two curves cut all circles at right angles: straight line and a tractrix.
I didn’t know what a tractrix was, so I Googled it! Tractrix definition from Wikipedia: Tractrix (from the Latin verb trahere ”pull, drag”; plural: tractrices) is the curve along which an object moves, under the influence of friction, when pulled on a horizontal plane by a line segment attached to a tractor (pulling) point that moves at a right angle to the initial line between the object and the puller at an infinitesimal speed.
Here’s a gif from Wikipedia showing a tractrix being created from dragging a pole:
Trevor Paglen - They Watch the Moon (2010)
"This photograph depicts a classified ‘listening station’ deep in the forests of West Virginia.
The station is located at the center of the National Radio Quiet Zone, a region of approximately 34,000 square kilometers in West Virginia and parts of Maryland.
Within the Quiet Zone, radio transmissions are severely restricted: omnidirectional and high-powered transmissions (such as wireless internet devices and FM radio stations) are not permitted.
The listening station, which forms part of the global ECHELON system, was designed in part to take advantage of a phenomenon called moonbounce.
Moonbounce involves capturing communications and telemetry signals from around the world as they escape into space, hit the moon, and are reflected back towards Earth.
The photograph is a long exposure under the full moon light.”
fuck yeah Trevor Paglen dot everything