Why does a SpaceX launch look like that over Arizona?
SpaceX launches look strange enough that people think aliens are invading. We asked a professor why that is. Professor Vishnu Reddy from the University of Arizona in Tucson, California, has explained why SpaceX rocket launches over Arizona appear to look like giant white comets or even rainbow-colored streaks in the sky. The phenomenon, known as the Twilight Phenomenon, occurs when the rocket launches far away from California but goes so high that it can be seen in Arizona, even though Arizona is not in the shadow of nightfall. The time of day, the direction of the rocket's travel, and the launch point are also factors. Reddy explains that the "glow" is sunlight hitting the exhaust trail, which can be detected even while the sun sets longer than it sets in California. Once the rocket reaches orbit, it will release a series of Starlink satellites.
Published : a month ago by Author: William Pitts in Tech Science
SpaceX launches look strange enough that people think aliens are invading. We asked a professor why that is.
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And it's easy to see why people would think it's something out of this world. When they're visible from Arizona, SpaceX rocket launches look like giant white (or sometimes rainbow-colored) comets or streaks in the sky.
Luckily, Arizona has a lot of rocket scientists to choose from to explain why they look like this.
Dr. Vishnu Reddy is a scientist at the University of Arizona in Tucson. He's worked for the Jet Propulsion Laboratory, studies space situational awareness and basically ... knows a lot about space.
He told 12News the reason those rockets light up the sky is not because the engines burn brightly (although they do), it's because of something called the Twilight Phenomenon.
"The sun might have set for us here in Arizona, but it hasn't set in California," Reddy said. "So it's catching that sunlight and reflecting off."
Basically, the rocket launches far away, in California. but it goes so high that we can see it in Arizona. And when we see it, it's not in the shadow of nightfall, even though Arizona is. The "glow" is sunlight hitting the exhaust trail, even while we perceive the sky to be black.
"If you are at the top of a mountain, you can see the sunset much longer than people at the base of the mountain," Reddy said. So, think of the rocket as the top of the mountain while you're at the bottom.
Reddy said it's a combination of the time of day, the direction of the rocket's travel, and the launch point.
SpaceX typically launches to the southwest of Los Angeles at an angle to take it away from populated areas. The rockets tip at a certain point and fly more horizontally to the ground than vertically, almost in a dogleg path.
But rockets in Florida, like those that launched the Space Shuttle, or even SpaceX's rockets in Florida, don't do that.
"If you're in Florida," Reddy said, "the rockets are launching right on top of you. You do get the plume, you do get the contrails and other things, but you're not going to be seeing what we're seeing."
And once the rocket gets into orbit, the 12News phone starts ringing again. Because this next mission is to release a series of Starlink satellites.
Topics: Space