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The Blue Angels are a U.S. Navy flight demonstration team that has been performing rolls, dives, and spins for inspired audiences around the world since 1946. If you have ever seen the amazing Blue Angels perform their gravity-defying maneuvers, then you have witnessed the power and beauty of the F/A-18 Hornet.
The F/A-18 Hornet flies fast—in fact, it can even fly faster than the speed of sound. But just how fast is the speed of sound?
The actual speed of sound varies depending on the altitude above sea level, because sound travels at slightly different speeds at different temperatures, and the temperature varies according to altitude. At sea level, the speed of sound is about 761 miles per hour. At 20,000 feet above sea level, the speed of sound is about 660 miles per hour, or 295 meters per second.
An airplane's speed is measured in different "Mach" numbers. Developed by the Austrian physicist Ernst Mach, the Mach number is the ratio of the speed of an object to the speed of sound. Therefore, a plane traveling at Mach 1 is traveling at the speed of sound. A plane traveling at half the speed of sound is traveling at Mach 0.5. A plane traveling at Mach 2 is traveling at twice the speed of sound.
Now, imagine you and your friends are at an air show. You've been waiting to see the F/A-18 Hornet all day. The announcer reports that it's now overhead—but you can't see it because it's flying so fast! After about a minute, you hear an enormous "BOOM!" You wonder, "What was that noise?"
What you heard is called a sonic boom. Here's how it happens: As the plane moves, it pushes air molecules out of the way in all directions at the speed of sound. When the airplane increases its speed to supersonic, or faster than the speed of sound, air pressure waves begin to pile up ahead of the airplane and compress, forming shock waves. When the shock waves hit your eardrum, there is a sudden change in pressure that you hear as a sonic boom. That loud "boom" lets you know that the Hornet has already flown by.
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