The invisible barrier of sound was overcome on October 14th, 1947, by a United States Air Force test pilot, Captain Charles "Chuck" Yeager, in a Bell X-1, which he christened 'Glamorous Glennis', after his wife. It was a remarkable achievement, and many future planes started to have the ability to reach Mach 1, which was equivalent to the speed of sound multiplied by 1, through the help of an afterburner, which consumed a lot of fuel, but after fifty years of technological advancement, the ability to supercruise, which is to fly at the speed of sound without afterburners and without consuming immense quantities of fuel, was made available. One such example is the F-22 Raptor.
The Speed of Sound is not a fixed constant, and varies at different air temperatures. However, it is commonly accepted that the general speed of sound is 1 234.8 kilometers per hour (767 miles per hour), which means about 1 mile in five seconds. This is only true when dry air is at 20 degrees Celsius (68 degrees Fahrenheit).
When an aircraft reaches the speed of sound, a vapor cone forms around the fuselage and a sonic boom is heard. Some planes can even achieve over Mach 3, such as the SR-71 Blackbird.