<p>An orbiting satellite becomes far more visible when there is a perfectly aligned angle between the sun, your eye, and a reflective surface on the satellite (usually the solar panels). Imagine looking in a very small mirror at arms' length to see a lamp across the room from you, if you want a more human-sized example. The light vanishes without going behind anything because the alignment changes as the satellite moves away from that perfect point. Imagine moving your mirror by an inch or so (without rotating it) and the lamp is no longer visible in the mirror. This is called a &quot;<a href="https://en.wikipedia.org/wiki/Satellite_flare" rel="nofollow noreferrer">satellite flare</a>&quot;. Some larger satellites (or, more often, space stations) are visible even without the perfect reflective angle, but modern communication satellites are usually too small to pick out with the naked eye without a flare.</p>
<p>Starlink satellites are launched in clusters that very slowly spread out towards their target orbits. The cluster appears as a line of satellites (called a &quot;train&quot;). A few days after launch, if you're in the right place at the right time, you'll see a string of a dozen or more lights in a perfect row. A few days later and they've spread out so that they won't be visible at the same time, but if you're in the right place, you can watch the train go by, each one hitting that perfect reflective angle and moving past before the next one arrives.  That's what you saw -- a series of reflective satellites coming by one after another.</p>

CC BY-SA 4.0
2023-09-09T13:29:14.377Z
This is it.  With starlink's launch cadence it is pretty common.  See https://satellitemap.space and spin the globe to see what trains there are.  Currently I count around 7 of them.  There are sites that allow you to try to observe them intentionally like https://findstarlink.com/
Seth Robertson
CC BY-SA 4.0
2023-09-10T08:05:37.973Z
Given that many satellites appear as points of constant brightness over a long stretch of sky, I think that that's the reflection by their body without special alignment. I think they disappear because they enter Earth's shadow.  A special alignment of solar panels or antennas cause a  [satellite flare](https://en.wikipedia.org/wiki/Satellite_flare).
Peter - Reinstate Monica
CC BY-SA 4.0
2023-09-11T14:44:34.743Z
@Peter-ReinstateMonica Yeah, I should be more clear that *some* orbital objects can be seen at any angle. What I meant was that *most* satellites are invisible to the naked eye without a flare.
Darth Pseudonym
CC BY-SA 4.0
2023-09-11T18:06:18.997Z
@DarthPseudonym Is that so? Apparently, even the small Starlink satellites are well visible as such.
Peter - Reinstate Monica
CC BY-SA 4.0
2023-09-11T19:03:04.543Z
@Peter-ReinstateMonica Starlinks are visible to the naked eye when they flare, and are visible most of the time on telescopes, but if they're visible to naked eye  in a dark-sky area when not flaring, then it's news to me.
Darth Pseudonym
CC BY-SA 4.0
2023-09-11T19:12:46.210Z
@DarthPseudonym [This article](https://www.space.com/starlink-satellite-train-how-to-see-and-track-it) as well as all the others I have read do not mention the need for telescopes, and you surely wouldn't be able to see a Starlink train if they'd only be visible when they flare (a flare is a short, extraordinary event). More recently, however, SpaceX made them darker than originally so they are harder to spot.
Peter - Reinstate Monica
CC BY-SA 4.0
2023-09-11T19:15:23.340Z
"...the long lines of lights are only visible shortly after launch. Once the satellites climb to their operating altitude of 340 miles (550 kilometers) they disperse and are far more difficult to differentiate against the backdrop of stars, though a timelapse photograph will pick them out easier."
Darth Pseudonym
CC BY-SA 4.0
2023-09-11T19:16:41.763Z
@DarthPseudonym More difficult to "differentiate" against the backdrop than the original train which really stands out. But not impossible to see at all. Anyway, these are really small and still visible; larger ones can be quite bright, as I can ascertain.
Peter - Reinstate Monica
CC BY-SA 4.0
2023-09-08T21:26:09.557Z
2023-09-11T19:06:33.320Z
2023-09-11T19:06:33.320Z
Darth Pseudonym
<h3>You may have seen <a href="https://en.wikipedia.org/wiki/A-train_(satellite_constellation)" rel="noreferrer">The A-Train or C-Train</a>!</h3>
<p><a href="https://i.sstatic.net/FfhFn.jpg" rel="noreferrer"><img src="https://i.sstatic.net/FfhFn.jpg" alt="enter image description here" /></a></p>
<p>Source: <a href="https://commons.wikimedia.org/wiki/File:A-Train_and_C-Train_constellations_-_2019-09.jpg" rel="noreferrer">File:A-Train and C-Train constellations - 2019-09</a></p>
<blockquote>
<p>...proceeding on a straight line out of the Dipper, then disappeared.</p>
</blockquote>
<p>These are in polar orbits which means their sightings <em>could be</em> associated with the Big Dipper. If there's more information (a rough lat/lon and time/date) we can look into that further.</p>
<blockquote>
<p>Anyways, oddly enough, half a minute or less later there it is again. Starts at same place and goes AWOL same place.</p>
</blockquote>
<p>If that's accurate, it narrows it down a bit. The two satellites shown in the image comprising the C-train are ~40 seconds apart, but the closest pair shown in the A-Train are about 2.5 minutes apart.</p>
<h3>About it always being Starlinks:</h3>
<p>While statistically because there are so many of them Starlink is <em>often</em> the answer to these types of one-satellite-following-another-following-another questions, it is far from the only game in town.</p>
<p><em>Previous examples</em> of groups launched together then spreading out over time are <a href="https://en.wikipedia.org/wiki/Cyclone_Global_Navigation_Satellite_System" rel="noreferrer">CYGNSS</a>, and, <a href="https://en.wikipedia.org/wiki/Planet_Labs#Flock_satellite_constellations" rel="noreferrer">Planet Labs' &quot;flocks&quot; of Dove cubesats</a> are also launched in clumps that over time slowly spread out in a similar fashion though perhaps <a href="https://space.stackexchange.com/a/64314/12102">taking more advantage of differential drag</a> than the more propulsive Starlinks do.</p>
<p>But the last flock was launched in January 2023 so they will be spread out now.</p>
<p>And don't forget SpaceX's early <a href="https://en.wikipedia.org/wiki/Orbcomm_(satellite)#Orbcomm-OG2" rel="noreferrer">Orbcomm-OG2</a> where a group of 6 and then a group of 11 satellites were each deployed together and then spread out in the same one-satellite-following-another-following-another fashion.</p>
<p>From <a href="https://space.stackexchange.com/q/13217/12102">https://space.stackexchange.com/q/13217/12102</a></p>
<blockquote>
<p><a href="https://i.sstatic.net/Ui4zF.png" rel="noreferrer"><img src="https://i.sstatic.net/Ui4zF.png" alt="enter image description here" /></a></p>
</blockquote>

CC BY-SA 4.0
2023-09-11T14:48:25.613Z
Aren't starlinks unusually reflective for their size, too?  I'm not sure Doves would even be visible during a flare, as tiny as they are.
Darth Pseudonym
CC BY-SA 4.0
2023-09-11T21:16:32.793Z
@DarthPseudonym you are right  - Starlinks shoujld be much brighter than Doves for several reasons including that they are deployed at much lower altitude (and use their own propulsion to raise themselves), they're bigger and at least in the past their attitude during the raising phase was more favorable for reflecting light. But we don't have magnitude (brightness) specified here and our eyes are logarithmic so I didn't feel it was right to *a priori* exclude them. I think "Are Doves visible from the ground after deployment?" would be a great new question!
uhoh
CC BY-SA 4.0
2023-09-10T01:55:38.567Z
2023-09-10T02:30:58.210Z
2023-09-10T02:30:58.210Z
uhoh
<p>This evening I was watching the <a href="https://en.wikipedia.org/wiki/Big_Dipper" rel="nofollow noreferrer">Big Dipper</a> when I noticed a bright-enough object (it looked either like a satellite or a really slow shooting star) a little above the line that connects <a href="https://en.wikipedia.org/wiki/Alpha_Ursae_Majoris" rel="nofollow noreferrer">Dubhe</a> and <a href="https://en.wikipedia.org/wiki/Delta_Ursae_Majoris" rel="nofollow noreferrer">Megrez</a>. It was visible for maybe 1.5 - 2 seconds, proceeding on a straight line out of the Dipper, and then disappeared.</p>
<p>I thought it was a satellite, but why did it disappear? There was not a cloud in the sky, so it couldn't have been hidden. Anyway, oddly enough, half a minute or less later there it was again. It started at the same place and goes <a href="https://en.wiktionary.org/wiki/AWOL#Adjective" rel="nofollow noreferrer">AWOL</a> in the same place. Now that was puzzling. But even more, I waited another half a minute and it appeared again for a third time. I was astonished - what could do that?</p>
<p>I'm not an expert, but I would rule out a satellite for the repetition of the trajectory in such a short time frame, as well as the shooting start as slow and impossible to have three in the same place at such a close timing. But what else?? Any clue? This is to me as close to UFO as I could ever realistically think about.</p>

CC BY-SA 4.0
2023-09-08T19:58:12.883Z
It could be a sequence of satellites, e.g. some newly-started starlink satellites which still follow somewhat a very similar orbit, thus reflect the sunlight to your observer position in the same place. Generally commenting on terrestrial or artificial phenomena, it needs a detailed time and place to make anything than general guesses
planetmaker
CC BY-SA 4.0
2023-09-08T20:04:02.977Z
You saw a set of Starlink satellites. I have seen numerous times (at least 3 different occasions) where satellite after satellite will flare low to the northern horizon for a second or two, then fade out. (They flare when the reflection of the Sun off of a surface is just right.) You might be able to confirm which set of Starlink satellites caused the flares by using Heavens-above.com. But with over 4000 Starlinks in orbit, it can be challenging to narrow it down.
JohnHoltz
CC BY-SA 4.0
2023-09-09T11:47:26.750Z
At what (local) time? At what (approximate) latitude? E.g., to establish if a ([LEO](https://en.wikipedia.org/wiki/Low_Earth_orbit)) satellite would be in the Earth shadow or not.
Peter Mortensen
CC BY-SA 4.0
2023-09-10T01:59:35.067Z
Yes, as I mention in [my answer](https://astronomy.stackexchange.com/a/54669/7982) it may be pretty straightforward to nail down exactly which satellites you saw if you can give an approximate lat/lon and time/date (note the time zone as well). The position in the sky is so specific I think there's a great chance of success here!
uhoh
CC BY-SA 4.0
2024-07-15T06:21:58.693Z
I just saw the same thing July 14, 2024 around 10:50 PM PST from northern CA. your description is typically what I just saw by Dubhe of Big Dipper. It felt stationary brighter star for the first second, the slightly moved and disappeared in the next two seconds. From the comments I learned here especially with the movement, it seems it is a satellite. I heard there could be a supernova to be seen from earth these months. I wish that was it, but now I can understand it is a satellite especially that someone described same event few years ago.
Some one
CC BY-SA 4.0
2024-11-12T15:22:35.453Z
Is no one reading he said one light starlink is a bunch in a line all lit up at once not one going out then showing then going off I have seen it 3 nights in a row in the same place only when it left the dipper it flashed really really bright and then flashed about 1 minute later on the other side of the sky
Will G
<observational-astronomy><amateur-observing>
Recurring flying object near the Big Dipper
Emanuele Canton
# Recurring flying object near the Big Dipper

(Asked by: username_0 on 2023-09-08)

This evening I was watching the [Big Dipper](https://en.wikipedia.org/wiki/Big_Dipper) when I noticed a bright-enough object (it looked either like a satellite or a really slow shooting star) a little above the line that connects [Dubhe](https://en.wikipedia.org/wiki/Alpha_Ursae_Majoris) and [Megrez](https://en.wikipedia.org/wiki/Delta_Ursae_Majoris). It was visible for maybe 1.5 - 2 seconds, proceeding on a straight line out of the Dipper, and then disappeared.

I thought it was a satellite, but why did it disappear? There was not a cloud in the sky, so it couldn't have been hidden. Anyway, oddly enough, half a minute or less later there it was again. It started at the same place and goes [AWOL](https://en.wiktionary.org/wiki/AWOL#Adjective) in the same place. Now that was puzzling. But even more, I waited another half a minute and it appeared again for a third time. I was astonished - what could do that?

I'm not an expert, but I would rule out a satellite for the repetition of the trajectory in such a short time frame, as well as the shooting start as slow and impossible to have three in the same place at such a close timing. But what else?? Any clue? This is to me as close to UFO as I could ever realistically think about.

**Tags:** observational-astronomy, amateur-observing
> **Comments:**
> **username_1**: It could be a sequence of satellites, e.g. some newly-started starlink satellites which still follow somewhat a very similar orbit, thus reflect the sunlight to your observer position in the same place. Generally commenting on terrestrial or artificial phenomena, it needs a detailed time and place to make anything than general guesses  
> **username_2**: You saw a set of Starlink satellites. I have seen numerous times (at least 3 different occasions) where satellite after satellite will flare low to the northern horizon for a second or two, then fade out. (They flare when the reflection of the Sun off of a surface is just right.) You might be able to confirm which set of Starlink satellites caused the flares by using Heavens-above.com. But with over 4000 Starlinks in orbit, it can be challenging to narrow it down.  
> **username_3**: At what (local) time? At what (approximate) latitude? E.g., to establish if a ([LEO](https://en.wikipedia.org/wiki/Low_Earth_orbit)) satellite would be in the Earth shadow or not.  
> **username_4**: Yes, as I mention in [my answer](https://astronomy.stackexchange.com/a/54669/7982) it may be pretty straightforward to nail down exactly which satellites you saw if you can give an approximate lat/lon and time/date (note the time zone as well). The position in the sky is so specific I think there's a great chance of success here!  
> **username_5**: I just saw the same thing July 14, 2024 around 10:50 PM PST from northern CA. your description is typically what I just saw by Dubhe of Big Dipper. It felt stationary brighter star for the first second, the slightly moved and disappeared in the next two seconds. From the comments I learned here especially with the movement, it seems it is a satellite. I heard there could be a supernova to be seen from earth these months. I wish that was it, but now I can understand it is a satellite especially that someone described same event few years ago.  
> **username_6**: Is no one reading he said one light starlink is a bunch in a line all lit up at once not one going out then showing then going off I have seen it 3 nights in a row in the same place only when it left the dipper it flashed really really bright and then flashed about 1 minute later on the other side of the sky  

---

## 2 answers

### Answer by username_7 on 2023-09-08. Score: 25

An orbiting satellite becomes far more visible when there is a perfectly aligned angle between the sun, your eye, and a reflective surface on the satellite (usually the solar panels). Imagine looking in a very small mirror at arms' length to see a lamp across the room from you, if you want a more human-sized example. The light vanishes without going behind anything because the alignment changes as the satellite moves away from that perfect point. Imagine moving your mirror by an inch or so (without rotating it) and the lamp is no longer visible in the mirror. This is called a "[satellite flare](https://en.wikipedia.org/wiki/Satellite_flare)". Some larger satellites (or, more often, space stations) are visible even without the perfect reflective angle, but modern communication satellites are usually too small to pick out with the naked eye without a flare.

Starlink satellites are launched in clusters that very slowly spread out towards their target orbits. The cluster appears as a line of satellites (called a "train"). A few days after launch, if you're in the right place at the right time, you'll see a string of a dozen or more lights in a perfect row. A few days later and they've spread out so that they won't be visible at the same time, but if you're in the right place, you can watch the train go by, each one hitting that perfect reflective angle and moving past before the next one arrives. That's what you saw -- a series of reflective satellites coming by one after another.

> **Comments:**
> **username_8**: This is it.  With starlink's launch cadence it is pretty common.  See https://satellitemap.space and spin the globe to see what trains there are.  Currently I count around 7 of them.  There are sites that allow you to try to observe them intentionally like https://findstarlink.com/  
> **username_9**: Given that many satellites appear as points of constant brightness over a long stretch of sky, I think that that's the reflection by their body without special alignment. I think they disappear because they enter Earth's shadow.  A special alignment of solar panels or antennas cause a  [satellite flare](https://en.wikipedia.org/wiki/Satellite_flare).  
> **username_7**: @Peter-ReinstateMonica Yeah, I should be more clear that *some* orbital objects can be seen at any angle. What I meant was that *most* satellites are invisible to the naked eye without a flare.  
> **username_9**: @DarthPseudonym Is that so? Apparently, even the small Starlink satellites are well visible as such.  
> **username_7**: @Peter-ReinstateMonica Starlinks are visible to the naked eye when they flare, and are visible most of the time on telescopes, but if they're visible to naked eye  in a dark-sky area when not flaring, then it's news to me.  
> **username_9**: @DarthPseudonym [This article](https://www.space.com/starlink-satellite-train-how-to-see-and-track-it) as well as all the others I have read do not mention the need for telescopes, and you surely wouldn't be able to see a Starlink train if they'd only be visible when they flare (a flare is a short, extraordinary event). More recently, however, SpaceX made them darker than originally so they are harder to spot.  
> **username_7**: "...the long lines of lights are only visible shortly after launch. Once the satellites climb to their operating altitude of 340 miles (550 kilometers) they disperse and are far more difficult to differentiate against the backdrop of stars, though a timelapse photograph will pick them out easier."  
> **username_9**: @DarthPseudonym More difficult to "differentiate" against the backdrop than the original train which really stands out. But not impossible to see at all. Anyway, these are really small and still visible; larger ones can be quite bright, as I can ascertain.  

---

### Answer by username_4 on 2023-09-10. Score: 13

### You may have seen [The A-Train or C-Train](https://en.wikipedia.org/wiki/A-train_(satellite_constellation))!

[![enter image description here](https://i.sstatic.net/FfhFn.jpg)](https://i.sstatic.net/FfhFn.jpg)

Source: [File:A-Train and C-Train constellations - 2019-09](https://commons.wikimedia.org/wiki/File:A-Train_and_C-Train_constellations_-_2019-09.jpg)

> ...proceeding on a straight line out of the Dipper, then disappeared.

These are in polar orbits which means their sightings *could be* associated with the Big Dipper. If there's more information (a rough lat/lon and time/date) we can look into that further.

> Anyways, oddly enough, half a minute or less later there it is again. Starts at same place and goes AWOL same place.

If that's accurate, it narrows it down a bit. The two satellites shown in the image comprising the C-train are ~40 seconds apart, but the closest pair shown in the A-Train are about 2.5 minutes apart.

### About it always being Starlinks:

While statistically because there are so many of them Starlink is *often* the answer to these types of one-satellite-following-another-following-another questions, it is far from the only game in town.

*Previous examples* of groups launched together then spreading out over time are [CYGNSS](https://en.wikipedia.org/wiki/Cyclone_Global_Navigation_Satellite_System), and, [Planet Labs' "flocks" of Dove cubesats](https://en.wikipedia.org/wiki/Planet_Labs#Flock_satellite_constellations) are also launched in clumps that over time slowly spread out in a similar fashion though perhaps [taking more advantage of differential drag](https://space.stackexchange.com/a/64314/12102) than the more propulsive Starlinks do.

But the last flock was launched in January 2023 so they will be spread out now.

And don't forget SpaceX's early [Orbcomm-OG2](https://en.wikipedia.org/wiki/Orbcomm_(satellite)#Orbcomm-OG2) where a group of 6 and then a group of 11 satellites were each deployed together and then spread out in the same one-satellite-following-another-following-another fashion.

From <https://space.stackexchange.com/q/13217/12102>

> [![enter image description here](https://i.sstatic.net/Ui4zF.png)](https://i.sstatic.net/Ui4zF.png)

> **Comments:**
> **username_7**: Aren't starlinks unusually reflective for their size, too?  I'm not sure Doves would even be visible during a flare, as tiny as they are.  
> **username_4**: @DarthPseudonym you are right  - Starlinks shoujld be much brighter than Doves for several reasons including that they are deployed at much lower altitude (and use their own propulsion to raise themselves), they're bigger and at least in the past their attitude during the raising phase was more favorable for reflecting light. But we don't have magnitude (brightness) specified here and our eyes are logarithmic so I didn't feel it was right to *a priori* exclude them. I think "Are Doves visible from the ground after deployment?" would be a great new question!  

---

