![A picture that shows the shock waves around a T-38 Talon aircraft on December 13, 1993.](https://npr.brightspotcdn.com/dims4/default/f193b2b/2147483647/strip/true/crop/748x600+0+0/resize/880x706!/quality/90/?url=http%3A%2F%2Fnpr-brightspot.s3.amazonaws.com%2Flegacy%2Fsites%2Fmichigan%2Ffiles%2F201404%2FSchlieren_photograph_of_T-38_shock_waves_0.jpg)
Credit Dr. Leonard Weinstein / NASA
/
NASA
Two parabolic mirrors, a barrier, a camera, and voilà! – you have a way to photograph sound waves – or more specifically, a way to photograph changes in air density.
Check out this video from NPR to see how it works:
http://youtu.be/px3oVGXr4mo
H/T Lucy Perkins