Found Lagrange moons!

[kepler68]

I was out exploring and noticed these two moons had nearly the same orbit. Went into EDDiscovery and verified they have the exact same semi major axis. They are placed at each other's L4 and L5 points, making them stable! I didnt realize Stellar Forge could generate Lagrange moons lol!

System: BYOO THEIA HA-O B20-0

Spoiler: EDDiscovery body data

 

[kepler68]

And I have tagged it since taking these pictures.

 

[Orvidius]

I do love these. Very nice find!

A little bit about Trojan orbits, and how the StellarForge gets it "wrong" in this case: For a body to be stable in the L4/L5 point of another, its mass needs to be smaller than a 1:25 ratio (minimal stability), and preferably smaller than 1:100 (highly stable). The L4/L5 points are 60 degrees ahead or behind the larger body within the orbit. There's some leeway here, as small bodies tend to orbit around the Lagrange point rather than sit directly in it. This is because the gravity well is actually more of a "dome" than a "bowl", and so objects will drift out of position, and Coriolis effects will keep it in a stable loop around the Lagrange point.

In game, moons like these are generally almost the same mass (which won't be stable at all), and often aren't that close to the 60 degree positioning (about 104 degrees in this case). They might even have slightly different periods, resulting in one gradually overtaking the other, passing it (or passing through it), and then separating again.

These are still always really cool to find though! And I think they're still pretty rare.

 

[kepler68]

I do love these. Very nice find!

A little bit about Trojan orbits, and how the StellarForge gets it "wrong" in this case: For a body to be stable in the L4/L5 point of another, its mass needs to be smaller than a 1:25 ratio (minimal stability), and preferably smaller than 1:100 (highly stable). The L4/L5 points are 60 degrees ahead or behind the larger body within the orbit. There's some leeway here, as small bodies tend to orbit around the Lagrange point rather than sit directly in it. This is because the gravity well is actually more of a "dome" than a "bowl", and so objects will drift out of position, and Coriolis effects will keep it in a stable loop around the Lagrange point.

In game, moons like these are generally almost the same mass (which won't be stable at all), and often aren't that close to the 60 degree positioning (about 104 degrees in this case). They might even have slightly different periods, resulting in one gradually overtaking the other, passing it (or passing through it), and then separating again.

These are still always really cool to find though! And I think they're still pretty rare.

I noticed they were in bad positions earlier today, but i had no idea the two objects had to have a mass ratio to stay stable lol!

 

[Sapyx]

The L4 and L5, or "Trojan" points, are at the vertices of equilateral triangles - the distance to the L4 and L5 points is the same as the distance to the parent.

So, when you're in the system of a suspected Trojan, the easiest way to test it is to fly to one of the three objects in the triangle, and check your distance to the other two objects. The distance readings should be identical. In the case of two moons closely orbiting a gas giant (as seen here in the OP), best results would be obtained by flying up close to (or landing on) one of the moons.

For further discussion of in-game examples, and for some data-mining of EDSM bulk data to find out just how common they really are, check out the Hunt for Trojans thread.