Shock wave is a sharp, intense disturbance or wave in a medium, such as air, water, or even the interior of a star. A weak disturbance generally travels at the speed of sound, a rate that depends on the medium. For example, at sea level and a temperature of 59 °F (15 °C), sound travels through air at 1,116 feet (340 meters) per second. Unlike a weak disturbance, a shock wave has enough energy to travel faster than the speed of sound.
The crack of thunder is a familiar example of a shock wave. Thunder occurs when lightning rapidly heats the surrounding air. As a result, the pressure of the air increases so much that it pushes a shock wave outward. When the rapid pressure increase reaches your ears, you hear a loud “crack.”
A sonic boom occurs when an object, such as a jet aircraft, travels through the air faster than the speed of sound. When the pressure of the passing shock wave reaches your ears, you hear a “boom.”
A supernova results when the core of a large star cannot produce enough energy to support its outer layers. These layers rapidly collapse onto the core, squeezing it until it stiffens. The infalling layers then rebound, creating a shock wave that travels outward, ripping the star apart.
