Closest black hole to Earth found 'hiding in plain sight'

A black hole merely 1,011 light years from our solar system is the closest ever discovered. Astronomers uncovered its presence while studying the binary star system HR 6819 in the constellation Telescopium. The central star orbits a mysterious object every 40 days or so, and the outer star encircles the central star and the object, which has a mass of 4.2 suns. A regular star of that size would shine brightly — so a black hole is the only option.