Is there a way to know if there are/are not solar-system-like systems of objects without a star? There's an extremely high amount of variation in All of Known Existence. We do see many many stars, with an extensive amount of evidence for planets orbiting around stars. However, is there are way to determine whether or not there's something like a 'dark solar system'? That's the only thing I can think of to call it.
This would be made out of a central body of mass, where the majority of material is located, with smaller planet-like objects in orbit around it, not unlike Pluto and its satellites.
Well, what about nearly-massive-enough-to-be-stellar objects? Why would there not be more of these - and the inevitable satellites involved in something of that mass - than there are solar systems?
I'm also assuming these would be made out of the same material that nearly everything else is, and I would expect them to be in abundance, so, could this explain the dark matter mystery? Assuming these dark systems are made out of the same - or mostly the same - material, wouldn't that also mean that spectral analysis wouldn't be able to determine if light from stars passed through the dark systems?
Intuition tells me someone has already debunked this, but I haven't been able to find an answer one way or the other. (yet)
Brown dwarfs (ie sub-stellar objects that are too small to support hydrogen fusion) do exist and some brown dwarfs have been found to host planets.  An example of this is the brown dwarf 2M1207.  It is a very dim object, about 25 Jupiter masses. It is still quite hot, so not completely &quot;dark&quot;, and it hosts a planet with a mass of 3-10 Jupiters.
There are doubtless other similar bodies, and smaller rogue planets with moons, though such bodies would be very hard to observe. Light would rarely pass through such a system (the gaps between systems are just too great) but if it did, the gravity of the system could cause light to be focussed.  This is called &quot;microlensing&quot; and is an observed phenomenon.
The idea that such bodies could explain dark matter is a good one, and it has even been given a name &quot;MACHO&quot; for &quot;Massive Compact Halo Objects&quot;.  The trouble with the MACHO hypothesis is that it doesn't fit with our understanding of how matter forms after the big bang. If matter behaves how we observe to behave, then there is no way that the big bang could have created enough normal matter to explain the observed amount of mass, this means that the excess mass must be in some other form, perhaps as a &quot;WIMP&quot; (Weakly Interacting Massive Particle) And yes the names were chosen to mirror each other.
We seem to live in a universe dominated by WIMPs and not MACHOs.