It sounds simple enough: Fly an Air Force T-38C jet trainer directly in front of the sun at supersonic speed; snap photo; use resulting photo for NASA research into shockwaves. But the resulting image, as seen here, is so much more than science: it's art.
The picture was created using a modified version of a photographic technique called "schlieren photography." Invented by German physicist August Toepler back in 1864, the technique uses a bright light source to reveal the energy waves in a fluid that's being disrupted by a fast-moving object. The Wikipedia page for this effect is a whole bunch of technical mumbo-jumbo, so we'll try and distill it down:
- Air is a fluid.
- Objects moving through a fluid make the fluid move around them. (See: wake.)
- Objects traveling faster than the speed of sound move the fluid fast enough to make the molecules freak out. (See: sonic boom.)
- When light hits these freaked-out molecules at a right angle, variations in the fluid cause the light to scatter in different directions.
- These differences in the ways the light passes through causes the pattern of freaked-out molecules to become visible.
The picture will be put to good use in NASA's hands. The aerospace agency's engineers are using this photo (and other schlieren images NASA has shot) to help visualize how air traveling at supersonic speed flows over aircraft in real life. This data, in turn, will be used to help NASA develop a quieter supersonic transport.
A photo that's both beautiful and could help put us inside a passenger jet that travels faster than the speed of sound? This picture deserves to be hanging inside the MoMA.