The January 2022 article for this column showed ways to tell the difference between meteors, airplanes, and satellites in the night sky. This month we are explaining some of the phenomena associated with rocket launches. There are increasingly more rocket launches these days, and more people wondering about their mysterious effects in the sky, so this time we’ll take a look at rocket signs resulting from rocket science.
Fire and smoke trails
If a rocket launch happens at night under clear skies, it can be seen from several hundred miles away. If you see a fiery light rising slowly into the sky and curving into a horizontal trajectory, you are probably seeing a rocket launch. When the rocket is within its first one and a half to two minutes of flight, it’s in the lowest and densest part of the atmosphere. Because of this, the fiery gases escaping from the rocket engine nozzles are kept in a narrow column. As the rocket rises higher, the gases bursting out of the rocket engine nozzles spread far and wide since there’s little to no air to resist its spread. At the same time, the red glow of the fire decreases and is replaced by a plume of smoke that can be seen from long distances since the rocket is very high at this point—literally more than sky-high. If the launch happens within a couple hours after sunset or before sunrise, then the sky is dark enough to see the high-altitude sun rays catching the glow of the expanding smoke plume.
Spirals
After a rocket has successfully reached orbit, it may jettison (dump) its excess fuel. If the rocket is spinning when this happens, it will create a spiral pattern in the sky. The spilled fuel will create a glow against the dark sky if the sun is positioned just below the horizon.
Todd Salat was near Delta Junction, Alaska, when he saw a rare display of this type in conjunction with a brilliant display of northern lights (see p. 27).
This is part of what he had to say about it:
“The second stage Merlin engine jettisoned its excess fuel to begin deorbiting, which caused the spiral motion. Water vapor in the fuel froze into crystals and spun outward into grandiose arcs and became illuminated by high-altitude sunlight, causing the bluish-white glow… This all happened as it passed over Alaska during a beautiful aurora display, stunning many night-watchers, including myself.
Lines and trains of lights
Some rockets carry a payload of fifty or more satellites. This is the case with the fairly common Starlink satellite launches, which can make for unusual sightings as well. Soon after launch, the satellites are released into orbit. At first, they can be close enough to each other to look like a line. Eventually, they spread farther apart and form a string of lights that appear like stars moving in single file across the sky.
Burning trails
There is only one way for a spacecraft to survive a reentry into Earth’s atmosphere. It must have a heat shield that is turned to face directly into the wind as the craft drops into the atmosphere. This is extremely important because of the friction caused by colliding into the air at speeds ten times faster than a speeding bullet. If the heat shield is missing or turned wrong, it’s a surefire way for the craft to come to a fiery end. It will simply burn up and break apart like meteors from space do. Even when everything is going as planned, you can actually see the layers of heat shielding burn away as a spacecraft returns to Earth. It looks like a slow-moving meteor with a very long burning tail.
If you think you may have seen one of these phenomena, you could check to see if a recent rocket launch coincides with what you’ve seen. There is a website that keeps a current schedule of past and future rocket launches from around the world. The web address is www.spacelaunchschedule.com.
The heavens were created with such an orderly and predictable nature that when something shows up that seems unexplained, it easily grabs our attention. It’s better to understand the natural causes rather than to succumb to confusion or hysteria over a supposed UFO.
