Recent finds of such planets have suggested that they may be common, but candidates have eluded close study.

The proximity of the new rogue planet has allowed astronomers to guess its age: a comparatively young 50-120 million years old.

The planet, dubbed CFBDSIR2149-0403, is outlined in a paper posted online to appear in Astronomy and Astrophysics.

Rogue planets are believed to form in one of two ways: in much the same way as planets bound to stars, coalescing from a disk of dust and debris but then thrown out of a host star's orbit, or in much the same way as stars but never reaching a full star's mass.

One tricky part is determining if rogue planet candidates are as massive as the "failed stars" known as brown dwarfs, further along in stellar evolution but without enough mass to spark the nuclear fusion that causes starlight.

Either way, the objects end up free of a host star's gravity. Given that most planets we know of are found through the effects they have on their host star's light, pinning down rogue planets has proven difficult.

An international team went on a vast hunt for the planets using the Canada France Hawaii Telescope on Hawaii's Mauna Kea and the Very Large Telescope (VLT) in Chile, looking for the infrared light that warm, young planets give off - and they came up with just one candidate.