Two international teams using the Hubble Space Telescope and ground-based telescopes in Australia and Chile have discovered the first black hole (6 solar masses) isolated in space within the Milky Way (all other black holes discovered so far have been either supermassive at the centers of galaxies or part of multiple systems). The gravity of the black hole (estimated to be 6 times the mass of the Sun) acts as a powerful lens (gravitational microlensing), bending and amplifying the light from a background star so that it appears as two separate images as the black hole slowly moves in front of it.
