The dark, Jupiter-like worlds are isolated and far from any host star.
Scientists believe they may have been ejected from developing planetary systems.
An international team of astronomers made the discovery from observations of the central 'bulge' of our galaxy, the Milky Way.
They found evidence of what appear to be ten free-floating planets with roughly the mass of Jupiter.
Dr David Bennett, from the University of Notre Dame in Indiana, said: 'Our results suggest that planetary systems often become unstable, with planets being kicked out from their places of birth by close encounters with other planets.'
The findings, published in the journal Nature, not only confirm that 'lonely planets' exist, but also that they are quite common.
Since they are very hard to spot, the discovery of ten at one time suggests they could be as common as those like Earth which orbit a host star. Read More