SPACE JELLYFISHFrom today’s SpaceX launch. Beautiful pic.twitter.com/98mzIGHDOMMay 6, 2022
In the early hours of Thursday morning (May 5), a camera in Waycross, Georgia witnessed a mysterious object streaking across the sky. Bright, fast, and followed by a glowing oblong aura, the object looked a bit like a space jellyfish, as Chris Combs, a professor of aerodynamics and mechanical engineering at the University of Texas at San Antonio, put it. On twitter.
Of course, as Combs pointed out, this space jelly wasn’t a UFO: it was a SpaceX Falcon 9 rocket Launch from the Kennedy Space Center in Florida, approximately 400 kilometers (250 miles) south of the chamber. Dozens of rockets roll off Kennedy’s launch pad each year, but few of them could be correctly mistaken for a bioluminescent invertebrate in the sky. So what happened here?
According to Combs, it’s a combination of physics and perfect timing.
For starters, the jellyfish’s long, bulging “body” is simply the exhaust coming out of the nozzle of the Falcon 9 rocket motor, Combs wrote. The reason the exhaust takes on such a bulbous shape has to do with the difference in pressure inside and outside the mouthpiece. In this case, the exhaust leaving the nozzle is “under-expanded”, meaning that the gas is at a higher pressure than the surrounding ambient air when the exhaust leaves the engine nozzle.
To match background ambient pressure in the atmosphere, rocket exhaust reduces its own pressure by expanding as soon as it leaves the nozzle, according to Combs.
“In the under-expanded exhaust, you get expansion fans at the nozzle outlet to lower the pressure and match the bottom: jellyfish, high up.” combs tweeted.
That explains the stain. But what about the glitter?
This is much simpler to square, Combs said, and it’s just about timing. Because the rocket launch occurred in the predawn hours of Thursday morning (about 5:45 a.m. local time), the light of Sun it came from just over the horizon, lighting up the exhaust plume, making it glow brightly against the dark sky.
Physics plus perfect timing equals space jellyfish. A simple equation for a high-altitude show.
Of course, if you want to see a real space jellyfish, you’ll have to look a little further into space – about 300 million Light years more to be exact. That’s how far away the galaxy cluster Abell 2877 is; When astronomers recently observed the object with a radio telescope, they saw the ghostly outline of a jellyfish swimming through distant space. That big jelly in the sky it is also the result of a large gas explosion; in this case, a massive eruption from a group of ancient black holes, Live Science previously reported.
Originally published on Live Science.