NASA engineers stare at the sun to see shockwaves from supersonic flight

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Before the eclipse this summer, NASA warned us over and over again not to stare directly at the sun — but now they’re doing just that. Its researchers have reinvented a photography technique more than a century old, using the sun itself as a backdrop in order to capture the shockwave produced by a new supersonic jet.

Schlieren imaging was invented by a German physicist in the 19th century as a way to capture objects moving at supersonic speeds; it basically works by tracking tiny distortions to a uniform background illumination that are produced when the air is disturbed by a passing object.

The results are striking and you’ve likely seen them before. But traditional Schlieren imaging is limited in its range and scale; NASA’s Background Oriented Schlieren using Celestial Objects (BOSCO) allows the sun itself to be used as the background, and, not only that, it’s reliable enough to be used from a chaser plane 10,000 feet up.

Another Schlieren photo from NASA that uses the edge of the sun as its uniform background; BOSCO uses the disc itself

Previous background-oriented Schlieren imaging efforts for viewing the distortion patterns of planes in flight have been shot top-down with a featureless landscape as their background, or bottom-up using the edge of the sun (as you see above). But BOSCO aims its telescopic camera directly at the disc of the sun, capturing the aircraft as it causes a partial, highly local eclipse.

In order not to be completely blown out, the camera system uses a “hydrogen alpha filter,” which only lets in a very specific wavelength of light, which is produced by the sun in a nice granular pattern.

You can see it in action in this video, which does double duty to remind you that much science is done in circumstances that are decidedly less than glorious but nevertheless awesome:

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