What is this "space jellyfish" observed in the sky of the United States?

What is this “space jellyfish” observed in the sky of the United States?

This is neither a meteorite nor a UFO, but a SpaceX Falcon9 launch highlighted by lucky timing.

Last Thursday at dawn, the inhabitants of the American state of Georgia were treated to a rather curious spectacle; several observers observed a mysterious phenomenon in the sky. A bright object moved at high speed in the sky, followed by a nice trail that made it look like “space jellyfish” according to several witnesses.

This is also the reaction of Chris Combs, a professor of mechanical engineering at the University of San Antonio when observing the video captured by Virtual Railfan. Yet it was not a meteorite or an unidentified flying object. It was actually a rocket SpaceX’s Falcon 9 from Kennedy Space Center, 400 kilometers away.

Even though these launches are becoming part of the routine for SpaceX, observers who have become accustomed to attending them regularly know that this visually very impressive phenomenon does not occur every time. Far from there. According to Combs, this “astonished” can only appear when several very specific conditions are met.

Perfect timing for a great show

The visible part of this cosmic mollusc is simply produced by the gases escaping from the rocket engine during the ascent. At this point in the ascent, the gas leaves the ejection nozzle with a pressure significantly above atmospheric pressure. However, the pressure and the volume of a gas are intimately linked (see the ideal gas equation); once this gas finds itself in this new environment, it is forced to adapt to it by increasing its volume.

It is because of this phenomenon that the drag is so voluminous. But that does not explain why it is possible to observe it when it is usually almost invisible. If the inhabitants of the southern United States were entitled to this beautiful spectacle, it is simply thanks to a luck of the timing.

LiveScience reports the words of Combs, who explains that the launch took place at dawn. Or more precisely, around 5:45 a.m. local time. Or a few minutes after the first rays of the Sun have pointed the tip of their nose. The star, the Earth and the rocket in the atmosphere were positioned so that the drag was lit from a particular angle; a stroke of luck which had the effect of make visible a few hundred kilometers below.

It is therefore a spectacle to which the locals could be entitled more and more often. SpaceX plans to significantly accelerate the pace of its launches. Once the famous Starship is commissioned, Musk even hopes to be able to chain launches all day long, starting at dawn. Good news for lovers of cosmic molluscs, for sure.

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