A team of astronomers from Poland has announced the discovery of the smallest of the Earth-sized "rogue planets", ie planets that do not orbit a star directly, to date, SciTechDaily reports.
According to the media outlet, such free-floating planets cannot be detected via traditional methods since they do not orbit a host star, but researchers from the Optical Gravitational Lensing Experiment (OGLE) project managed to achieve this feat by employing microlensing.
"If a massive object (a star or a planet) passes between an Earth-based observer and a distant source star, its gravity may deflect and focus light from the source. The observer will measure a short brightening of the source star," explains Dr Przemek Mroz, a postdoctoral scholar at the California Institute of Technology and a lead author of the study. "Chances of observing microlensing are extremely slim because three objects — source, lens, and observer — must be nearly perfectly aligned. If we observed only one source star, we would have to wait almost a million years to see the source being microlensed".
The discovery of the "shortest-timescale microlensing event ever found", designated OGLE-2016-BLG-1928 and which has the timescale of 42 minutes, was reported by scientists on 29 October.
"Our discovery demonstrates that low-mass free-floating planets can be detected and characterised using ground-based telescopes," said Professor Andrzej Udalski, head of the OGLE project.