The speed of sound (dry air) is .21 miles per second, 1,125 feet per second, 768 mph.

The speed of light is 186,291 miles per second, 983,616,480 feet per second, 670,616,629 mph.

A light-year is a unit of length equaling 5.88 trillion miles. It is the distance light travels in one 365-day year.

One Mach is 767 mph.  The name “Mach” came from the Austrian physicist Ernst Mach who in 1887 conducted an experiment photographing an object moving faster than the speed of sound.

Categories of flight speed:
          • Subsonic speed is under 609 mph
          • Transonic speed is between 610 and 914 mph
          • Supersonic speed is between 915 and 3,806 mph
          • Hypersonic speed is between 3,807 and 7,680 mph
          • Highhypersonic speed is between 7,681 and 19,031 mph
          • Re-entry speeds are greater than 19,031 mph

Transonic speed takes place with swept wings, wings that angle backwards like a typical jet.

Supersonic speed takes place with thin swept wings that are often blended into the fuselage.

Reentry speed occurs with small or no wing, a heat shield and a blunt shape.

A sonic boom is loud noise that occurs from the shock waves created whenever an object travels through the air faster than the speed of sound.

The fastest aircraft on record is NASA’s X-43, traveling at Mach 9.6 or 7,366 mph.  This hypersonic unmanned aircraft uses a scramjet engine and can reach an altitude of 110,000 feet or 20 miles.