Núria Miret-Roig, first author of this study, remarks that "the discovery of this large population of young FFPs has important implications for the formation and early evolution of planetary systems and, specifically, on the timescale of the processes involved. Our observations suggest that giant-planet systems must form and become dynamically unstable within the observed lifetime (3-10 million years) of the region to contribute to the population of FFPs. Current studies suggest that dynamical instability among the giant planets in our Solar System may also have occurred at early times, although it was much less violent than the instability needed to eject planets as massive as the ones we have found."

FFPs, lurking far away from any star illuminating them, would normally be impossible to image. However, the astronomers took advantage of the fact that, in the few million years after their formation, these planets are still hot enough to glow, making them directly detectable by sensitive cameras on large telescopes.

Moreover, Hervé Bouy, project leader of the new research, emphasises that "the FFPs we identified are also excellent targets for follow-up studies. In particular, they will be essential to study planetary atmospheres in the absence of a blinding host star, making the observation far easier and more detailed. The comparision with atmospheres of planets orbiting stars will provide key details about their formation and properties. Additionally, studying the presence of gas and dust around these objects, what we call 'circumplanetary discs’, will shed more light on their formation process".

"Assuming the fraction of FFPs that we measured in Upper Scorpius is similar to that of other star forming regions, there could be several billions of Jupiters roaming the Milky Way without a host star. This number would be even greater for Earth-mass planets since they are known to be more common than massive planets."