This animation shows the orbit of the star S2 around the supermassive black hole at the heart of the Milky Way. At its closest approach, which occurred most recently in May 2018, the star is traveling at nearly 3% of the speed of light and is an ideal test object for studying very strong gravitational fields and testing Einstein's general theory of relativity.
Credit: ESO/L. Calçada/spaceengine.org