A few months ago I observed an event so rare that I doubt anybody has ever seen anything like it. I should have recorded the details at the time, but I was too busy with other tasks, and only today did I remember that I should at least record it.
Every time SpaceX launches a new batch of StarLink satellites, they are visible for a week or two before they rise to higher orbits. They appear as a string of pearls moving together through the sky; the apparition is enchanting. You can find predictions for these events at the Heavens Above website — but you’ll have to set up an account and enter your latitude and longitude. You’ll need only to get within one minute of arc of accuracy to get accurate results.
I check into the website every now and then to see if there are any good StarLink passes coming up. One night back in October I was outside waiting for a good pass with my wife and a friend. Right on time, the first satellite appeared. They were rather widely separated, so I knew it would take some time to see them all. After several satellites had come and gone, I found what I thought was the next one in the sequence — but it appeared to be off the track taken by the previous satellites. I watched it closely and confirmed that, while close, it was definitely NOT following the same path as the preceding ones. Then I discovered the correct next satellite in the original sequence. With a start, I realized that I was seeing a second stream of StarLink satellites. Before I had time to digest the significance of this event, I noticed another satellite moving in a completely different direction. I dismissed it as likely one of the many other satellites that pass over any given location. A few moments later I saw yet another following that same path.
At this point, things grew too complicated for me to keep track of. At any given moment, there might be half a dozen StarLink satellites visible, following three different paths. They were all near the bottom end of the brightness range I can see (perhaps magnitude 3.0 to 3.5), so I had to seek carefully to find each one. They were all widely separated — about one minute apart for each of the three streams. But after seeing at least half a dozen members of each stream, I knew that I truly was seeing three separate StarLink streams passing overhead at one time.
Having watched StarLink satellites for five years now, I know this to be an especially rare event. I get a good evening pass (satellites brighter than magnitude 2.5) maybe every few weeks. To get two passes in one night has happened a few times, but the passes were usually separated by as much as an hour. But to get three passes at the same time — that’s got to be a very rare event. I’m sure that it happens; after all, they have several launches each week. But I suspect that the only people who have seen such an event are those who constantly monitor the predictions, looking for this kind of thing.