On: Blackbird SR-71 Flight Manual (2010)

[NortySpock]

Point 3 goes against normal behavior of hot metals, which emit infrared or visible light as they get hotter. It's called black-body radiation, and it's why iron and steel glow in a blacksmith forge.

The "moving parts" may be due to heat waves moving through the air (see also: mirage at a distance)

[serf → NortySpock]

>Point 3 goes against normal behavior of hot metals, which emit infrared or visible light as they get hotter.

You're right. People refer to it as 'transparent' because it begins to glow the same color as the jet plume under afterburner use.

https://gizmodo.com/this-is-an-image-of-the-very-last-test-o...

[ncmncm → NortySpock]

Differential heating could give the illusion of transparency; really it would just be the metal glowing brighter where something hotter is on the other side.