EghtesadOnline: Two aircrafts were traveling so fast — quicker than the speed of sound — and so close together that the shock waves emanating from the craft began to merge… and NASA was there to capture photographic proof.
The resulting snapshots are the first-ever photos of two supersonic shock waves (pressure waves) interacting in the air. And it is quite a sight: It looks as though the atmosphere folded up into a fresh batch of laundry, space.com reported.
As an aircraft travels, it pushes the air in front of it and creates waves, just like a motor boat creates waves as it moves through the water.
But when aircraft travel faster than the speed of sound — or faster than 1,235 km/h — it moves faster than the waves it creates. Because air molecules cannot keep up with its speed, they begin to compress, according to Financial Tribune.
This creates a rapid increase in pressure in front of the craft, resulting in a different kind of wave: supersonic shock wave. Though humans cannot see these shock waves, we can hear them merging together as they move through the atmosphere as a thunder-like sound called a sonic boom.
In the recent event, NASA's air-to-air schlieren photographic technology captured images of mingling shock waves from two T-38 supersonic US Air Force Test Pilot School airplanes. These craft fly about 9 meters from one another and at a 3 m difference in height, according to a NASA statement.