Flug von Aruba nach Norden über den Atlantik in einer Höhe von über 35.000 Fuß. Der Kapitän teilte mit, dass ein Start von Cape Canaveral aus erfolgen würde. Als der Abhebevorgang unsere Höhe erreichte und dann passierte, war das Fahrzeug von einem nahezu perfekten kreisförmigen Lichtkranz umgeben. Ich hatte gehofft, dass jemand das erklären könnte "Warum" Für mich!
https://i.redd.it/5f8a3relfcfg1.jpeg
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It looks like a stage separation is about to occur… 🤔
I believe it’s when the sun below the horizon reflects off the exhaust gases!
The exhaust plume of the rocket (note this is an approximation) receives a constant mass of particles over the burn time; however, the ambient pressure around the rocket drops as it ascends. This means that the exhaust of the rocket expands to fill a larger volume and appears more uniform as atmospheric effects drop off over altitude.
This typically isn’t visible because the ambient light of daytime is far brighter than light bouncing off the plume, but when the sun is below the horizon, the exhaust can still be illuminated, and will be far brighter than the sky and ground around it.
TLDR: it’s the exhaust.
The exhaust comes out of a circular nozzle. So it spreads out perfectly in a circle from the low pressure.
The exhaust is made up of combustion products (CO2, water vapor, and soot) which initially starts out at thousands of degrees. In the near vacuum of the extreme upper atmosphere the exhaust plume spreads out in a semi-spherical shape, because there’s nothing to hold it in. As it expands it cools rapidly, forming tiny ice crystals and water droplets. When the launch occurs just before sunrise or just after sunset there’s a chance for the exhaust cloud to be in direct sunlight and visible from portions of the ground (or from a plane) which are locally in darkness, making the cloud extremely visible.