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I believe that I recently saw a Starlink launch (details below in case I am mistaken); what puzzled me was that it appeared as a blurred, hazy line or streak. I watched it move across the sky and at one point it briefly resolved into individual points of light before going back to the blurred line.

My question is why did it look like this? Could it be caused by high level clouds that were thin enough to not be seen otherwise, or by gas (propellent?) around the satellites, or something else?

I saw it just after midnight BST from the UK on 8th June. Weather was clear. I was in town, so not great viewing, but most streetlights go off at midnight where I live so could have been worse.

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  • $\begingroup$ The satellites are too small for your eyes to resolve. Also possible the gaps between them were too small for your eyes to resolve. The result is an ambiguous image your brain has trouble interpreting. I thought they looked like a contract the first time I saw them in a tight line. $\endgroup$ Commented Jun 17 at 0:28
  • $\begingroup$ Don't suppose you took a photo? From your story it sounds plausible that something may have passed behind a wispy cloud. I don't think it's appropriate to contemplate all possible sources of blurring as a space exploration question. $\endgroup$
    – Wyck
    Commented Jun 17 at 15:52
  • $\begingroup$ When you said it was just after midnight on the 8th, did you possibly mean it was the night of the 8th and just past midnight, so technically the first hour of the 9th? $\endgroup$ Commented Jun 18 at 15:22

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There was no Starlink launch around this time, therefore, you can't have seen a Starlink launch.

There was a Starlink launch on the 8th a couple of hours later in the morning and another one in the afternoon. The last one before the date you mentioned was 3 days before on June, 5th.

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Any launch from the U.S. will not be visible in the UK because the launch vehicle and payload are in orbit long before it reaches Europe. As seen in this view from SpaceX of the Starlink 10-1 launch on June 7th at 9:56 pm EDT (June 8th at 2:56 am BST (British Summer Time)), at the moment of SECO (Second Stage Engine Cut-Off) the Falcon 9 second stage was off the northeastern coast of the United States when it reached orbit.

Starlink 10-1 launch track diagram



What can be seen from the UK are on-orbit burns, or the second stage booster or released satellite(s) or propellant dumps if the lighting conditions are right. In the case of Starlink 10-1 the second stage was still carrying the Starlink satellites when it passed over England about thirty minutes after launch at 03:25 BST, based on using the Heavens Above website to sort of reverse engineer the vehicle position on that date.

Starlink visible pass

The above data was generated using the current TLE (Two-line element set) for the twenty-two deployed Starlink satellites. This makes it somewhat inaccurate for calculating the vehicle position ten days earlier, for example you can see that the individual Starlink satellites are shown as already separated by some distance, which would not be the case shortly after launch. And in this case the satellites had not even been released yet (as will be discussed below). But it should be close enough for our purposes here, as it gives at least some idea of where the second stage was shortly after the launch on June 7th (June 8th BST).

The Heavens Above website shows this ground track at 03:25 BST on June 8th:

Starlink 10-1 ground track UK

Local sunrise in London on June 8th was 4:44 BST, so the second stage would have probably been visible as it passed overhead, as would any burns that may have taken place at that time.

However as mentioned the Starlink satellites had not been deployed yet at this time, they were deployed nearly an hour after the launch, according to a post by SpaceX at 03:55 BST on June 8th:

Starlink deployment tweet



According to Space.com, satellite deployment occurred 52.5 minutes after launch, although I'm not sure where they got this information from since it was not included in the SpaceX post. That would have put the Starlink deployment on the other side of the world, near Australia or somewhere around there. By the time the deployed satellites came around again they would have passed farther to the west and probably been too low on the horizon to see very well from the UK, besides it also being shortly after sunrise which would have made it pretty much impossible to see them.

If you are sure that it was close to midnight the morning of June 8th when you saw whatever it is that you saw, then it would not have had anything to do with the launch of Starlink 10-1. If you have a slightly better estimate of what time it was, approximately where you were viewing from, where in the sky you saw it and what direction it was moving it might be possible to better determine what it is that you saw.

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