From time to time NASA launches small rockets at night that produce artificial luminescent clouds in space. The goal is not to inspire UFO watchers and conspiracy theorists, but rather to aid studies of Earth’s ionosphere and aurora.
By spraying known vapor tracers – in this case composed of barium, strontium and cupric oxide – and observing their movement and behavior at heights of 150 kilometres and more above Earth, sceintists can glean a great deal of information.
This photo shows one such test, at Wallops, North Carolina.