Inner Moons List

In our universe so called shepherd moons -- moons with orbits inside planetary rings, that limit the "herd" of the ring particles with their gravity -- are not something very unusual. In fact, all four gas giants in our system have both rings and moons inside them.

Recently we've got some absolutely amazing photos of Pan (one of Saturn's shepherd moons) with it's "crest" -- equatorial ridge made, probably, from the material of the ring.


Here are some more real-world shepherd moons photos:
Prometheus near the ring of Saturn:


Daphnis inside a ring gap and gravitational waves on the edges of the Saturn's rings:


Galatea near the arc in the Neptune's ring:

In theory every time we in Elite Dangerous see nice-looking rings with gaps like that:
we should have expected to see shepherd moons. However in ED universe things are quite different and moons inside rings are rather rare.

That is, I believe, because of the size limit for bodies, created by Stellar Forge engine. As far as I know the smallest moons ever found in ED Galaxy have radius of about 137 km.

The majority of real shepherd moons are of about that size or even smaller. For instance the mentioned Pan is only 34.4×31.4×20.8 km. So, I guess, the majority of ED's possible shepherd moons were filtered out during the creation of the Galaxy.

This makes the existing ones even more rare and valuable.

I know that some explorers collect rarities. GGGs and trojans are good examples. However to my great surprise I didn't manage to find a list of already discovered moons inside rings, though I know for sure that there are people collecting them.

To correct this injustice, I decided to open this thread with a special table :)

So, coming to the more practical part. How do you find shepherd moons in ED?

It's easy!*
* No, it's not :D

1) First of all, a lot of commanders have already scanned those moons and added the data to EDSM.

By the way, I have a disclaimer for you: if you don't already use EDSM and special tools to fill this database automatically from your logs -- please do! By filling this ED's analogue of Big Data you are helping a lot of different commanders in a lot of different ways, some of which you can't even imagine!

And thanks to cmdr. Orvidius we now have an almost complete list of scanned to EDSM moons inside rings.

Why do I say "almost"? Well, that's because due to some technical issues it doesn't include shepherd moons inside the innermost ring (they are difficult to differ from binary moons). And such moons, though rare, do exist. To be honest, we currently know just six documented systems:

Blae Flyuae OY-H d10-0







Bleia Flyuae RZ-F c11-3



Eoch Blao AA-A h65

Mylaifa AA-A h786 (aka Ocularis Coelum)





Scheau Byoe DB-U d4-1013





and Wepae AA-A h22 (aka Mors et Vitae)



However, like I've mentioned before, the list is not full and technically we can not be 100% sure that such systems are that rare :)

The full list of moons inside ring gaps for now contains about 40000 (yes 40k!) of moons. However shepherd moons usually come in quantities from 2 to 5 per system. But still that gives us about 10k of known gas giants (and sometimes brown dwarfs, water giants, ammonia worlds and even icy bodies) with shepherd moons inside their rings. That's still quite a lot. But, on the other hand, not at all as much as ELWs :)

2) How do you differ ringed planet with shepherd moons from the one without?

Well you can look at the orrery map. However, keep in mind that the map seems to be unwilling to show some rings sometimes.

Then you can look at the parameters of the rings. If you see a ring with radius over 1Mkm or if the ring system has large gaps (like the inner ring ends at 200 Kkm and the outer starts at 1,2 Mkm) -- it may be worth checking.

Moons with short orbital period (like less than a day) may also be of potential interest. However, keep in mind that if the moon is binary, system map doesn't show it's actual orbital period (the time it takes moon to rotate around it's parent body), only the period of the rotation of the two moons around each other. Unfortunately, we currently have no idea of how to deal with that situation.

3) Some rings are different from the others ;)

In ED some of the largest rings (quite a lot of them, actually) have a tendency of being too sparse and dark to be seen. Some commanders have already complained about it and got an answer from the FDevs that this is actually OK:)

I'll quote:
Water World Planet 2 A in aforementioned system is shown having Metal Rich Rings in system map but none are present in regualr game view

Thanks for your report - This looks to be working as intended.
And that actually has sense, for in our own home system only one of the four ringed gas giants has rings that are bright enough to be seen without some special treatment :)

However in ED we do need some way to differ invisible rings from visible ones (except from boldly going there and checking manually :)). And it looks, that cmdr. Gromsch has some ideas about that!

I'll quote the conclusions part from his analytics:

  • Invisible rings are most likely icy.
  • There seems to be a line (top left to bottom right) that devides the visible and non visible rings in both plots.
  • There still is an area of uncertainty around that line.
  • My guess is, the visibility of rings close to that line depends on the distance of their parent body to the central star and the bightness of the central star*.
  • We need more data :D.
*This would mean the in-game lightning model also controls the physical interaction as some invisible rings can be just flown through.

By the way, looking at those photos one might guess, that shepherd moons are only rocky or icy worlds. That is very common, of course, but not quite true. There are known shepherd ELWs: Byoi Ain LS-I d10-1919 body #7 A.






Now as for the lists.

I've already mentioned the almost complete list of scanned to EDSM moons inside ring gaps made by cmdr. Orvidius. It can be found here.

The original table of inner moons from this post is now here, but due to technical reasons it will not be updated any more.

Sorry, the "new" forum mechanics seem to hate tables, so the complete table of documented bodies with shepherd moons will temporarily be located at GoogleDocs:
INNER MOONS LIST
I'll make filters there as soon as I understand how to share them :)

There also were (and will be more, I hope) some regular searches for the shepherds moons. And here are the results:
List of shepherd moons in Myriesly sector.
List of shepherd moons in Bleia Flyuae sector.

We do need some pictures to attract attention. So here we go, here are some nice examples of ED's large rings and shepherd moons:

2MASS J18190744-1640266 body #6

Alnitak (It is near the Bubble, by the way!)

Bleia Flyuae ZU-N d7-54 body #10

Byoi Eurk LM-W e1-10 body #6

Droju QD-X b6-1 body #3

Dryeae Brai IU-K c10-0 body #3

Eol Prou GC-L d8-16 body #AB 1

Eol Prou QI-B e1809 body #8

LTT 16019 (yes, it is in the Bubble too!) body #3

Pru Eurk WA-U c4-2 body #7

Qosoa AA-A h56 body #2



Skaudai KI-C b58-1 body #4 (aka Cúpla Iontach)



Splierd UD-B D1 body #8


If you've run into more shepherd moons, please post your reports in this thread!
 
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I've met the mention of Traikaae SN-X C28-61 planet AB 3 as the one, that might have moons inside it's outer ring. Unfortunately there were no clear screenshots, and, what is worse, I can't remember where it was mentioned and by whom.

I will check the system myself eventually, but if someone is now not far from Omega Mining and can make those screenshots -- I would be very grateful :)
 
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I know that some explorers collect rarities. GGGs and trojans are good examples.

However to my great surprise I didn't manage to find a list of discovered moons inside rings, though I know for sure that there are people collecting them.

To correct this injustice, I decided to open this thread with a special table :)

I know there are way more, and I even have some on my list, but for now I've got photos only of this listed systems. Hope to check more myself.

And hope for help: if you've run into more moons inside ring systems, please post your reports here.
A nice idea.

Just a note Shnyrik, most moons between rings, that is in the gap are called "shepherd moons" because they actually maintain the gap by herding wandering fragments back into the ring itself.

https://en.wikipedia.org/wiki/Shepherd_moon

I prefer the term shepherd moon myself but as you are the progenitor of this list it's entirely up to you.
 
Hm, I have at least one, Lysoosms TS-U d2-328 1 a. It's a landable moon, and its neighbour 1 b (which is outside the rings) is an ammonia world. However, it looks like I forgot to take a screenshot of the planet inside the rings itself when I was there. So the only proof would be the system data, and the orrery view now:
 
And a new one: Ooscs Freau ZY-S d3-1486 B 2. According to sysmap it was once opened by cmdr Steyla.



 
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And one more, thanks to cmdr. DartBatiatus: Byoi Eurk LM-W e1-10 6.




I'll quote cmdr. DartBatiatus's description:

It was a Y star with 3 planets between the rings and gas giant on screen outside. Star was 6 main body from entry. There were also some pumpkins in this system but not around this particular star.
 
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And we have one more system reported by cmdr. D.D.Hariman: LTT 16019.


There is also a video in the post.

The most surprising for me is that the system is actually in the Bubble! I've checked it on EDSM and EDDB and despite the outer ring of gas giant #3 is not very large (from 0,6 to 1 Mkm) the first binary moons #3a and #3b seem to be inside it.
 
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And we have one more system. Had to make a detour from DW2 route, but here it is in all it's glory: Wepae AA-A h22.

It is better known as EDSM POI Mors et Vitae for it has two black holes with an earthlike companion, but it also has an M-class red dwarf star #ABC 1 with enormous ring and planets inside it.



 
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Not quite an inner moon, but I imagine this one deserves an honorable mention (it definitely doesn't conform to real life physics)


The surface is only about 300 kilometers from the edge of the rings, compared to its radius of 1500 km. How this ring could exist for more than like, a month, is beyond me.
 
You can add NGC 7822 Sector BQ-Y d12 in the NGC 7822 Nebula to the list. Moon A 3 A and A 3 B are inside the rings of a Gas Giant with ammonia-based life. It's an inhabited system with an asteroid base in the inner ring of A 3.


 
Dryooe Prou ZS-S b4-17 4 A

system: Dryooe Prou ZS-S b4-17 / ~1085ly from Colonia
parent body: Dryooe Prou ZS-S b4-17 4 / class I gas giant / 3 rings
shepherd moon: Dryooe Prou ZS-S b4-17 4 A / between 2nd and 3rd ring
image:
notes: Visually unspectacular. The 3rd ring is not visible (for me) from space, but can be found in the system map and orrery.
 
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