An extreme orbit The galactic centre hosts a spinning supermassive black hole surrounded by many orbiting stars. One star approaches the central black hole so closely that its orbit (shown in orange) is altered by spin-inducing effects. (Credit: ©MPE)"> An extreme orbit The galactic centre hosts a spinning supermassive black hole surrounded by many orbiting stars. One star approaches the central black hole so closely that its orbit (shown in orange) is altered by spin-inducing effects. (Credit: ©MPE)

At the centre of our galaxy lies a supermassive black hole, Sagittarius A* (Sgr A*), that’s more than four million times the mass of the Sun. Astronomers have now discovered the fastest-known star in the Milky Way zooming around this black hole in an extremely close orbit. Observations of this star, known as S301, could shed new light on the spin of Sgr A*.

Black holes are extremely large concentrations of matter condensed into very small regions of space.…