Mach number a small area around the object's leading edge. (Fig.1b) Fig. 1. "Mach number in transonic airflow around an airfoil; M < 1 (a) and M > 1 (b)." When an aircraft exceeds Mach 1 (i.e. the sound barrier), a large pressure difference is created just in front of the aircraft. This abrupt pressure difference, called a shock wave, spreads backward and outward from the aircraft in a cone shape (a so-called Mach cone). It is this shock wave that causes the sonic boom heard as a fast moving aircraft travels overhead. A person inside the aircraft will not hear this.
Mach 1: A Story of Planet Ionus Mach 1: A Story of Planet Ionus Mach 1: A Story of Planet Ionus is a 1957 science fiction novel by Allen A. Adler. A paperback version was published in 1966 by Paperback Library with the alternate title Terror on Planet Ionus. While testing an experimental warship, the "Mach 1", a human pilot and his companion are kidnapped into space by aliens from the planet Ionus, which turns out to be a moon of Saturn. There, they confront an oversized monster named Karkong who is menacing the Ionians. Karkong follows them back to Earth. Chaos ensues. Damon Knight wrote of