05:55 GMT04 December 2020
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    Since planets such as the one that was discovered do not orbit any host star, scientists had to employ some not-so-traditional methods to spot it.

    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.
    study, detection, planet, Poland
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