Youtube video of the Iridium-6/GRACE-FO NASA Launch (Falcon 9 SES-12).

Edit 31 May: Too bad they have changed the content of the video (and still call it 'live'), so that you can no longer see the entire launch phase. You can still see that in this video showing the entire launch.

There's one ring visible at the top of the rocket after 1:30 minutes into the launch and it seems to emit light:

enter image description here

Shortly after 1:50 into the flight, you see 3 more 'rings' developing:

enter image description here

This is after going supersonic (1:11) and maximum dynamic pressure (1:24).

They must be some sort of bow waves/shock waves. But:

  • Why is there only one, later 4?
  • Do they (especially the top one) really emit light?
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    $\begingroup$ The rocket itself seems badly out of focus in these shots; I would guess the supersonic shock wave structure is refracting sunlight in a way that happens to focus sharply in the camera. The shock wave structure changes with air pressure and rocket velocity, so the refraction pattern changes over time. Nothing other than the sun is emitting light. $\endgroup$ – Russell Borogove May 29 '18 at 14:46
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    $\begingroup$ Those are artifacts produced when the rocket enter's the wormhole. Similar artifacts are simultaneously produced at the other end of this unique, one-of-a-kind stable wormhole in the Milky Way galaxy. $\endgroup$ – uhoh May 29 '18 at 15:06
  • 4
    $\begingroup$ They look like out of focus highlights captured with a mirror lens $\endgroup$ – matteol May 29 '18 at 17:27
  • $\begingroup$ Wild guess: burning hydrocarbons makes CO2 and H2O, (CH2 + 1.5O2 = CO2 + H2O) The steam on the outside ring is in contact with and diffuses into the very cold air at 20 to 30 km and condenses quickly, whereas in the middle it takes much longer to cool by radiation so it won't condense right away. That's why LOX/RP-1 rockets are called "Steam Engines". Oh wait, they're not? $\endgroup$ – uhoh May 31 '18 at 0:44

This donut shaped ring is the typical bokeh of a mirror lens. Evidently, the tracking camera was failing to achieve good focus nearly all the time. Unfocused point of light (e.g. specular reflection from the sun) gets the shape of the camera aperture, which is donut, because of the secondary mirror obstruction (distorted further by the atmospheric turbulence).

Wikipedia: Bokeh

Wikipedia example (rings visible in the unfocused background) bokeh example from wikipedia

Catadioptric (mirror) lens:

catadioptric telescope

NASA article showing their long range tracking cameras using some kind of catadioptric lens.

  • $\begingroup$ Bingo! Beautiful answer, this is so obvious now that you mention it. Ha, someone even proposed a wormhole in comments. More mirror lenses in this question and the answers there as well. $\endgroup$ – uhoh May 31 '18 at 21:10

I think we don't need sonic boom condensation to explain it. If you look at photos, for example here https://spaceflightnow.com/2018/05/24/photos-blues-skies-make-for-spectacular-falcon-9-launch-in-california/

it can be seen that the rocket have white and dark parts:

1.White upper part - it's paiload fairing and second stage

go down

  1. Dark interstage. Used only second time, before that interstage was painted white.

3.White upper part of the first stage

4.Some darker lower part of first stage because of soot from previous flight (this first stage was used to launch Zuma payload on Jan. 7 2018)

why 5th lowest white area occurs? At photos we see also landing legs, and they are white. So I think at second picture the leg is just more prominent, due to changed lighting conditions (different sun-rocket-camera angle, plus maybe the rocket have rotated)

P.S. I watched all Falcon 9 launches, but never noticed any sonic boom effect. Did anybody?


The likely explanation here is sonic booms. For the most part, everyone knows that passing mach 1 creates a sonic boom. Doing some research, it seems that there are specific angles and thus specific surfaces on a craft that result in a sonic boom rather than the entire craft. Due to the complexities of fluid mechanics around the spacecraft, it is not unlikely to believe there are several surfaces for which the entire craft has to hit speeds above mach 1 to result in a boom. When a boom is created, an extreme compression wave moves outwards causing the water vapor in the air to condense in a similar fashion to cloud formation to my understanding. This would reflect light and due to the thin nature of the cloud produced, appear to give off light. As for the ring shape, this would just be due to the cylindrical shape of the faster moving air shroud around the craft forcing the brief instance of a boom formed cloud into a circular shape.

Edit: As many have mentioned, this is probably not correct, but I will leave it just in case it's helpful to the discussion.

  • 1
    $\begingroup$ Can you provide any examples of a multi-shock system that was photographed on an axisymmetric booster? (Not shuttle) $\endgroup$ – Organic Marble May 30 '18 at 22:59

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