It's about one-third as fast as The Space Shuttle.
In other words, 8.4 mach is 0.35966 times the speed of The Space Shuttle, and the speed of The Space Shuttle is 2.7804 times that amount.(Orbiter vehicle velocity)
The space shuttle orbits at a speed of 23.356 mach. During liftoff, the space shuttle accelerates to orbital speed in 8.5 minutes, consuming over 1.59 million kg (3.51 million lbs) of propellant in the process.
It's about three times as fast as a Bullet (Rifle).
In other words, 8.4 mach is 3.04 times the speed of a Bullet (Rifle), and the speed of a Bullet (Rifle) is 0.329 times that amount.(5.56 x 45 mm, a.k.a. 5.56 NATO)
A 5.56 x 45 mm cartridge is fired at a velocity of 2.76 mach. As the NATO rifle cartridge, it is used by the military forces of more than thirty-one countries, including use in the M16 series, M4 Carbine, HK-416, and M249 Squad automatic weapons used by the United States armed forces.
It's about four times as fast as a Jet Fighter.
In other words, 8.4 mach is 4.2 times the speed of a Jet Fighter, and the speed of a Jet Fighter is 0.24 times that amount.(for Lockheed Martin F-16, a.k.a. Fighting Falcon, a.k.a. Viper) (maximum speed at altitude)
An F-16's maximum speed at altitude is approximately Mach 2. The F-16 has a flight ceiling of approximately 15 km (9.32 mi).
It's about seven-and-a-half times as fast as a Bullet (Handgun).
In other words, 8.4 mach is 7.25 times the speed of a Bullet (Handgun), and the speed of a Bullet (Handgun) is 0.138 times that amount.(for .40 Smith & Wesson 135 grain Sierra JHP, VV 3N37 powder, Fed. 100 primer, Remington case) (muzzle velocity)
A 0.40 caliber Smith & Wesson bullet has a muzzle a velocity of 1.16 mach. This type of ammunition has been the standard issue round of the United States Federal Bureau of Investigation (FBI) since 1990.
It's about eight times as fast as The Speed of Sound.
In other words, 8.4 mach is 8.12 times the speed of The Speed of Sound, and the speed of The Speed of Sound is 0.123 times that amount.(in dry air at 20°C)
The speed of sound in dry air at 20°C (68°F) is 1.03 mach. Air is a relatively poor acoustic conductor, however, as sound will travel at speeds of between 4.52 mach to 4.71 mach in water, depending on its salinity.
It's about one-fifteenth as fast as a Meteor.
In other words, the speed of a Meteor is 15 times 8.4 mach.(formally Meteoroid or meteorite, depending on the context; a.k.a. "shooting star", a.k.a. "falling star")
Small meteoroids enter the Earth's atmosphere at speeds between 34 mach and 220 mach, depending on their size. The fireball effect, known as ablation, ceases once the atmosphere has slowed the meteoroid to a velocity of about 8.4 mach.
It's about thirty times as fast as a Peregrine Falcon.
In other words, 8.4 mach is 25.8 times the speed of a Peregrine Falcon, and the speed of a Peregrine Falcon is 0.0388 times that amount.(a.k.a. Peregrine, a.k.a. Duck Hawk, Falco peregrinus)
The Peregrine Falcon can reach speeds of up to 0.326 mach when diving. Falcons are sometimes sent to scare smaller birds away from airports to improve air traffic safety and were used in World War II to intercept carrier pigeons used by enemy forces.