There’s a “rogue planet” flying through the Milky Way galaxy — a free-floating world without a host star. Is it actually a Death Star? The worldships of Marvel villains Annihilus or Galactus? The planet-sized Transformer Unicron? In the year 2020, surely anything is possible but, alas, no.In a newly published study, scientists announced they have discovered a rogue planet. It appears to be on the smallish side as far as exoplanets go, with a mass reportedly between that of Earth and Mars.
“Our discovery demonstrates that low-mass free-floating planets can be detected and characterized using ground-based telescopes,” announced the study’s co-author Andrzej Udalski, principal investigator of the Optical Gravitational Lensing Experiment (OGLE) project led by the University of Warsaw in Poland.
— SPACE.com (@SPACEdotcom) October 29, 2020
While astronomers have discovered 4,000 exoplanets to date — and that there may be far more rogue planets out there than there are planets with host stars — detecting a rogue planet is more difficult than it seems because there’s no light from a host star for scientists to use to help spot the planet.
The OGLE project, utilizing the Las Campanas Observatory in Chile, spotted the rogue planet using a technique known as gravitational microlensing.
As Space.com explains, this planet-hunting method, “involves watching foreground objects pass in front of distant background stars. When this happens, the closer body can act as a gravitational lens, bending and magnifying the star’s light in ways that can reveal the foreground object’s mass and other characteristics.”
The study’s lead author, Przemek Mroz at the California Institute of Technology, explained just how “extremely slim” the chances of such a microlensing event are because it requires perfect alignment of the light source, the telescope lens, and the observer. “If we observed only one source star, we would have to wait almost a million years to see the source being microlensed,” Mroz said.
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For more science news, read up on the evidence of a parallel universe where time runs backward, a cosmic cloud that has some people claiming “Galactus is coming!“, NASA’s discovery of water on the moon, a black widow star that’s a source of gamma radiation, the frightening 50-50 chance that we really are living in a simulation, and watch footage of the Osiris-Rex probe touching down on an asteroid.