Shocking Photos

At Live Science, Tia Ghose writes about a photography project that captures the shock waves a jet makes when it crosses the sound barrier.

And all it took was a 150-year old technique to do it. You can read the full explanation at the link, but basis deals with the fact that both the jet and the sound it makes affect air density, which in turn affects the way light passes through the air.

The method was first developed in 1864 by Austrian physicist August Toepler. He, of course, did not use it to photograph jets going supersonic, there being nether jets nor airplanes nor much understanding of how fast sound traveled. Scientists upgraded Toepler's technique to be used on moving planes traveling fairly close together at high rates of speed. Their insurance company promptly upgraded their premiums.

And there was an actual real-world purpose to the experiment, which will help scientists study how the shock waves of sound-barrier breaking affect things nearby.