This illustration provided by the European Southern Observatory in May 2020 shows the orbits of the objects in the HR 6819 triple system. The group is made up of an inner binary with one star, orbit in blue, and a newly discovered black hole, orbit in red, as well as a third star in a wider orbit, blue. The team originally believed there were only two objects, the two stars, in the system. However, as they analysed their observations, they revealed a third, previously undiscovered body in HR 6819: a black hole, the closest ever found to Earth, about 1000 light years away. The black hole is invisible, but it makes its presence known by its gravitational pull, which forces the luminous inner star into an orbit. The objects in this inner pair have roughly the same mass and circular orbits. (L. Calçada/ESO via AP)