Rogue planets roam in space without orbiting a star, and now scientists have found two more of these floating worlds.
For centuries, the very existence of rogue planets was hypothetical. Because they are not close to a star that illuminates them, they are tremendously difficult to spot. Then came a technique known as gravitational microlensing.
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Using gravitational microlensing, scientists find the planets by noticing when a rogue planet interrupts the light of a star from our point of view. The planet suddenly acts as a lens for the light of the star, bending it as we would see from the Earth. The larger the planet, the greater the interruption.
It is not the most efficient system. Some astronomers (such as Neil DeGrasse Tyson) estimate that there are billions of rogue planets within the Milky Way. But while humanity has proved very good at finding extrasolar planets attached to the stars, scientists have identified only a dozen thieves. This is what makes a big problem adding two more to the stack.
The planets are officially called OGLE-2017-BLG-0560 and OGLE-2012-BLG-1323, respectively, and there is a lot that we do not know about them. Their names derive from how they were discovered at the Optical Gravitational Lensing Experiment at the Las Campanas Observatory in Chile. The first could be anywhere from the size of Jupiter to the size of 20 Jupiters, while the second is between the size of the Earth and Neptune. Nothing is known about how far they are from the solar system.
Scientists hope that the Transiting Exoplanet Survey Satellite, launched on April 16, offers exoplanets and planet hunters a new advantage in learning more about the mysterious bodies that apparently surround the solar system.