CAPE CANAVERAL, Fla. — A sonic boom shocked Central Floridians early Sunday morning when the Air Force landed a secret military aircraft at Kennedy Space Center.

The Air Force tweeted Sunday morning that “The Air Force #X37B #OTV4 has returned from orbit and landed safely at @NASAKennedy.”

The X37B is a secret unmanned military shuttle, which as been orbiting the Earth for more than a year on its fourth flight.

The landing marks the first time the X-37B has landed at KSC using the same Shuttle Landing Facility runway as NASA’s manned orbiters.

"X-37B program is the newest and most advanced re-entry spacecraft that performs risk reduction, experimentation and concept of operations development for reusable space vehicle technologies," the Air Force said.

Several people were calling and emailing Channel 9 asking us what the loud boom was Sunday morning.

Sonic Boom: Here's how it works

The image below from NASA illustrates three aircraft. The first is traveling slower than the speed of sound. The second, at Mach 1, the speed of sound. The third, faster than the speed of sound.

Air is a fluid and sound travels through it as waves, so for an aircraft traveling faster than the speed of sound, these waves will be altered. Air particles get pushed aside in pattern similar to how a traveling boat creates a cone-shaped wave front.

The cone-shaped wave front travels outward as a shock wave. It produces a sonic boom along the full width of the cone's base along the ground, as shown by the graphic below by Pearson Education Inc.

The weight, size, shape of the aircraft, along with the altitude, flight path and weather, can all impact or distort the sonic boom.

See the landing of the spacecraft below:

Cox Media Group