What Supersonic Looks Like

The breaking of the sound barrier is not just an audible phenomenon. As a new picture from the U.S. military shows, Mach 1 can be quite visual. This widely circulated new photo shows a Air Force F-22 Raptor aircraft participating in an exercise in the Gulf of Alaska June 22, 2009 as it executes a supersonic flyby over the flight deck of the aircraft carrier USS John C. Stennis. The visual phenomenon, which sometimes but not always accompanies the breaking of the sound barrier, has also been seen with nuclear blasts and just after space shuttles launches, too. A vapor cone was photographed as the Apollo 11 moon-landing mission rocketed skyward in 1969. The phenomenon is not well studied. Scientists refer to it as a vapor cone, shock collar, or shock egg, and it's thought to be created by what's called a Prandtl-Glauert singularity.

Here's what scientists think happens: