70 ‘Rogue Planets’ Have Just Been Discovered In Our Galaxy

Cameron Frew


70 ‘Rogue Planets’ Have Just Been Discovered In Our GalaxyAlamy

The truth is out there: astronomers have somehow discovered at least 70 ‘rogue planets’ in our galaxy. 

According to NASA, ‘rogue planets float freely through the universe, without the gravity of a star or planetary system to hold them in one place… you could say they’re dancing among the stars’.

Unlike the eight planets in our solar system (nine if you’re a Pluto defender like me), rogue planets are ‘elusive cosmic objects’ floating across the universe. They were once difficult to discover, but the advancement of telescope technology has allowed astronomers to find their glow in the vast expanse.


Using 20 years of data from the European Southern Observatory telescopes and other facilities, a team of astronomers found the largest group of rogue planets ever discovered, ‘an important step towards understanding the origins and features of these mysterious galactic nomads’, as per a press release.

‘We did not know how many to expect and are excited to have found so many,’ Núria Miret-Roig, an astronomer at the Laboratoire d’Astrophysique de Bordeaux and the University of Vienna, as well as the first author of the study published in the Nature Astronomy journal, said.

An example of a rogue planet. (ESO/M. Kornmesser)ESO/M. Kornmesser

Not only do the planets have masses comparable to Jupiter’s, but they were discovered in a star-forming region close to our Sun. ‘We measured the tiny motions, the colours and luminosities of tens of millions of sources in a large area of the sky. These measurements allowed us to securely identify the faintest objects in this region, the rogue planets,’ Miret-Roig explained.

‘The vast majority of our data come from ESO observatories, which were absolutely critical for this study. Their wide field of view and unique sensitivity were keys to our success,’ Hervé Bouy, an astronomer at the Laboratoire d’Astrophysique de Bordeaux, added.

‘We used tens of thousands of wide-field images from ESO facilities, corresponding to hundreds of hours of observations, and literally tens of terabytes of data.’

Formation of rogue planets. (ESO/N. Risinger)ESO/N. Risinger

Their origins are also unclear, but new discoveries allow astronomers to find clues on how they may have formed; for example, some scientists believe they may have come from the collapse of a gas cloud too small to lead to the formation of a star.

It has been noted that the exact number of planets discovered is difficult to pin down – however, it is estimated to be anywhere between 70 and 170, and there may be even more. ‘There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star,’ Bouy said.

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Topics: Science, NASA, Now, planets, Solar System, Space, universe


  1. ESO

    ESO telescopes help uncover largest group of rogue planets yet

Cameron Frew
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