stronomy Picture of the Day - Triple Shockwave from Sun Crossing Rocket

Explanation: What's happening to this Sun-crossing rocket? The SpaceX Falcon 9 rocket, visible on the upper left, launched only about one minute before this amazing image was captured. As it rose to low Earth orbit from Cape Canaveral, Florida, USA, in late May, the rocket became supersonic before it crossed the disk of the distant Sun -- from the perspective of the well-placed photographer. The spacecraft's high speed caused bow-shaped compressed-air shockwaves to form across leading surfaces, with at least three visible even outside the Sun's disk because they refract sunlight. The trailing exhaust caused turbulence visible on the lower right. None of this was damaging to the robotic Starlink 10-53 mission, which delivered 29 communications satellites to low Earth orbit as planned. And if that isn't amazing enough - the Sun had spots!

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For more detail go to the link and click on the image for a high definition image. You can then move the magnifying glass cursor then click to zoom in and click again to zoom out. When zoomed in you can scan by moving the side bars on the bottom and right side of the image.

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A really interesting photo composition. Be sure to click on the image at the link to get the high definition photo where you can zoom in on the shock waves using instructions in the first post.

“So...approaching MACH 3?”

Approaching, yes

At the moment the pic captured, the rocket was probably around Mach 1.2 +/-

Bow shockwaves at 45° is about mach 1.4

So...approaching MACH 3?

No, I think it was passing through mach 1. The shock wave near the rocket is at an angle of about 45 degrees meaning the shock wave was moving away at the same speed as the rocket moved along the trajectory. You can see at the outer portions of the shock waves that the wave curves, showing that the speed of sound outward was greater then the speed of the rocket when the shock wave formed.

The trigonometry of the picture with the rocket movement (up or adjacent side of the right triangle), The shock wave is moving out (opposite side of the right triangle formed at the nose of the rocket). At the speed of sound up is equal to out so the sides of the triangle are 1 and 1. The Arc Tangent (opposite divided by adjacent sides) is 1. Arctan of 1 is 45 degrees. If the rocket was travelling twice the speed of sound then up = 2 and out (speed of sound) = 1. Opposite divided by adjacent = 1/2. Arctan of 0.5 = 26.56 degrees. The shock waves are going at a greater angle than Mach 2. And Mach 3 would produce shock waves at an angle of 18.4 degrees. The three shock waves are caused by different dynamics. The upper one is caused by air being displaced ahead of the rocket. The second shock wave is caused by air impacting the payload fairing which is the nose cone of this type of rocket. The third shock wave is from turbulence at the back end of the rocket, likely the fins and the blast from the rocket engines.

I used to work in this industry, more on the satellites, but some on the rockets.

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