A roughly Earth-sized, 'free-floating' planet roaming across the Milky Way — while gravitationally unattached to any star — has been discovered, a study reported. Astronomers from the US and Poland say that this so-called 'rogue planet' is the smallest ever identified to date. While most known planets orbit a star, the team believe our galaxy may be teeming with rogue planets — possibly outnumbering the number of stars in the ...