Free-floating ‘rogue’ planets the size of our Earth wander freely through space in our galaxy – and could, perhaps, even host life.
A new study by a team of University of Warsaw researchers investigated the number of these ‘rogues’, using a technique called gravitational micro-lensing.
The researchers used Poland’s Optical Gravitational Lensing Experiment (OGLE), a 1.3-meter telescope in Chile.
The researchers found that large, Jupiter-size planets could be less common than previously believed – with just a tenth of the number expected.
But smaller, Earth-sized worlds, hurled out of their solar systems into interstellar space, could be much more common.
Previous research by University of Aberdeen researcher Sean McMahon suggested that such planets might harbour life beneath the surface.
‘Basically, it is much easier to eject an Earth-mass planet than a Jupiter-mass planet,’ said researcher Przemek Mróz of the University of Warsaw.
Mroz, a PHD student, said: ‘We detected a few possible ultrashort-timescale events, less than half a day, which may indicate the existence of Earth-mass and super-Earth-mass free-floating planets, as predicted by planet-formation theories.
‘The shortest-timescale events are not well covered by observations and it’s difficult, if not impossible, to either prove or disprove their nature as free-floating planets.
‘The detection efficiency at these timescales is very low, meaning a very few detections imply the existence of a large population of Earth-mass free-floating or wide-orbit planets.
‘Future space-based missions like WFIRST and Euclid will enable the exploration of these short events in more detail.’