When an object goes supersonic, or faster than the speed of sound, it produces a shock wave. While this may not be visible to the naked eye, NASA has made it possible to see the wave, as can be seen below.
According to earthsky.com, this image shows a jet flying at supersonic speeds while passing in front of the sun. You can see the shock waves on both sides of the aircraft. The dark spots on the disk are sunspots. The NASA researchers that captured this image used an old German photography technique called Schlieren imaging. NASA explains that the shock waves appear darker because changes in the air density affect how much light is refracted. NASA wrote:
Shock waves are narrow regions of air where pressure, temperature, and density characteristics are drastically different than surrounding areas. Shock waves occur when objects move faster than the speed of sound, which is 1,236 kilometers (768 miles) per hour.
Below is another perspective from NASA Earth Observatory, which was taken with a high-speed camera from another aircraft above the one in the image, over the Mojave Desert.