Planet orbiting "nothing"

PeteACarter

P
I know you sometimes find a station orbiting "nothing" because comets have not been implemented, but today I found two planets orbiting "nothing", one with a mass of 3.5 earth masses.

There was a slow down in the centre of the orbit but nothing to be seen.

What object large enough to have such a large planet orbiting it have not been implemented?

https://twitter.com/x/status/1280246115359653888
Source: https://twitter.com/RaxxlaHunter/status/1280246115359653888?s=20


https://twitter.com/x/status/1280177989221863424
Source: https://twitter.com/RaxxlaHunter/status/1280177989221863424?s=20
 
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Thwarptide

Banned
Thwarptide
I've seen it plenty of times. It has everything to do with gravitational effects. Two or more bodies having equal influence on each other can create the illusion that something should be in the middle.
I've seen dual sun solar systems where sun and planets seem to be orbiting nothing. One sun would have all the planets while the larger sun did not, yet both seemed to orbit nothing. The gravity of the larger sun with no planets was equal to that of the smaller sun with many planets.

Planets do this too.
I've seen single planets do it around nothing. Made me wonder, but I didn't care enough to investigate.

Buuuuut, I've also seen single sun systems (no planets) with ecliptic orbits around nothing. FSS scan showed nothing (no black hole). I shrug my shoulders and chaulk it up to FD re-writing the laws of physics and move myself along elsewhere.
 

Sapyx

Sapyx
They're not "orbiting nothing", they're orbiting each other. Or rather, they're orbiting around their mutual centre of gravity, the "barycentre". The Wikipedia article on barycentres gives several animated GIFs on how different masses of planets/suns affect the shape of the orbits. Your "two planets orbiting nothing" are actually doing this:
Orbit2.gif

The "+" in the middle is the barycentre.

Out there in the real universe, all objects orbit around a barycentre. For objects where the primary or larger body is many, many times bigger than the secondary, the barycentre is usually buried deep inside the primary. The Earth-Moon barycentre, for example, is buried about 1700 km beneath the Earth's surface. In ED, such "internal barycentres" are simplified away and the primary does not wobble about. But if the ED Stellar Forge creates a star-star or planet-moon barycentre that is above the surface or outside of the primary, then it creates a binary star/planet with a barycentre.

Out there in the real universe, situations where multiple bodies are orbiting each other - like all the planets orbiting around the Sun - things get incredibly complicated, even chaotic. The Stellar Forge cannot cope with chaotically dynamic systems so in ED things are simplified by reducing everything to a nested series of two-body barycentres. Thus, in a system like this:
RsCdZIk.png


We have nested barycentres: Planets 1 and 2 orbit the {1+2} barycentre; planet 3 orbits the {{1+2}+3} barycentre, planet 4 orbits the {{{1+2}+3}+4} barycentre, and planet 5 orbits the {{{{1+2}+3}+4}+5} barycentre.
 
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PeteACarter

P
Thanks all. Some good explanations.

In terms of ED - If they are purely orbiting a barycentre, why would there be a "slow down" in the centre?
 

marx

marx
The stations in Pareco aren't orbiting nothing: they are orbiting a comet. The Stellar Forge generates those, but since the objects themselves aren't implemented yet (and at this pace, I wonder if they ever will), their POIs are hidden, and with their frame of reference being 50 km, you have to determine their location really precisely in order to drop on them. Seeing only empty space though, only way you'll know is that the location readout will say this:
rl7646W.png


Of course, how six stations can orbit a comet is an entirely different matter.
 

Orvidius

Orvidius
Non Grata said:
Do you lean back to put the barycentre over your feet?
Click to expand...

Technically yes, since the barycenter is the mutual center of gravity, and the center of gravity needs to be supported. However, there are of course ways around this, such as constantly moving to support it intermittently, or using gyroscopic effects to permit supporting it off-center. But for the most part, it's going to mostly be over your feet in that sort of example.
 

varonica

varonica
marx said:
The stations in Pareco aren't orbiting nothing: they are orbiting a comet. The Stellar Forge generates those, but since the objects themselves aren't implemented yet (and at this pace, I wonder if they ever will), their POIs are hidden, and with their frame of reference being 50 km, you have to determine their location really precisely in order to drop on them. Seeing only empty space though, only way you'll know is that the location readout will say this:
rl7646W.png


Of course, how six stations can orbit a comet is an entirely different matter.
Click to expand...

They don't, there would be multiple problems, apart from the obvious one that a cometary orbit is named after comets and you wouldn't want stations caught in a cometary orbit when it passes close to the star. There wouldn't be enough gravity to keep the stations in orbit, and a comet is notoriously unstable anyway, an outgassing from heating as it gets near the sun can change the orbit completely, so it's obvious they aren't. If the invisible comet is indeed there they are just following along it's path in a particularly unusual gravitational pattern called a Klemperer Rosette, it's essentially unstable over the long term and would require frequent minor corrections, however it's stable enough in the short term. Since it's essentially a research base they could be researching the invisible comet I suppose.
 
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