I believe we will some day discover that galaxies are filled with miniature "Solar Systems" comprised of commonly orbiting Sub-solar sized debris. They'll range in size from multiple Brown Dwarf systems (with associated moons, moonlets and belts of debris); down to golf ball sized systems - and even smaller!<br /><br />For a long time, astronomers have resisted the idea that Sub-solar systems were common; they theorized that stars (with their accompanying planets, etc.) were the only logical result of the accretion disc process. <br /><br />It's my opinion that these Sub-solar systems are very common in galaxies; but unfortunately, they're very difficult to detect because they are just too dark to see. <br /><br />Vast numbers of these small un-illuminated systems would contribute to the missing mass (Dark Matter) which <i>we know</i> galaxies must contain, but are unable to detect; and since we can't see it, we're not sure what it's really comprised of...<br /><br />These small systems would likely form from dust and debris starved areas of Stellar Nurseries; much like normal Solar Systems form.<br /><br />The recent discoveries of large Extrasolar planets and other independent Brown Dwarf sized celestial objects seems to support this view and makes me think there's a lot more of this stuff out there! But for now it's all just conjecture... <br /><br />I'm betting we'll eventually discover several Brown Dwarf sized systems between us and our nearest stellar neighbors; (and no, I'm not trying to start a "Planet X" argument...). <img src="/images/icons/rolleyes.gif" /> <br /><br />I think this simple concept makes perfect sense -- it's a discovery waiting to happen!.