Researchers in Poland have spotted a brightening of a star which they believe was caused by a Mars-sized planet moving in front of another star.
They said that there could be millions of planets rocketing through the solar system that are not accompanied by a parent star, therefore holding no gravity of their own.
A planet such as this is known as a “rogue” planet and the one discovered is slightly smaller than Earth.
A reseacher from the Californian Institute of Technology, Dr Przemek Mroz, said “The odds of detecting such a low-mass object are extremely low. Either we were very lucky, or such objects are very common in the Milky Way. They may be as common as stars.”
A phenomenon known as “microlensing” was the cause of the planet being spotted.
Microlensing is when the planet bends the light from the star behind it, and is based on Einstein’s theory of relativity.
Dr Mroz went on to explain “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. 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 incredible event was named OGLE-2016-BLG-1928 and lasted just 42 minutes. Dr Radoslaw Poleski from the Astronomical Observatory of the University of Warsaw said “When we first spotted this event, it was clear that it must have been caused by an extremely tiny object. Indeed, models of the event indicate that the lens must have been less massive than Earth – it was probably a Mars-mass object.”
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