Fastest star S301 discovered near Sagittarius A*

Astronomers using the European Southern Observatory's Very Large Telescope Interferometer have discovered the fastest known star in the Milky Way, designated S301. The star orbits the supermassive black hole Sagittarius A* at the galaxy's center, completing an orbit every 8.7 years. At its closest approach, it travels at about 25,000 kilometers per second, over 8% of the speed of light, and comes within roughly the distance of Saturn from the Sun. This unprecedented proximity makes S301 sensitive to the black hole's spin, potentially allowing scientists to measure the rotation of Sagittarius A* for the first time, a key test of Einstein's general relativity. The discovery was published in the journal Nature on August 19, 2026. The research team, led by scientists at the Germany — Max Planck Institute for Extraterrestrial Physics, traced the star's orbit back to 2017 and expects its next close approach in 2031, which could provide the data needed to measure the black hole's spin within the next decade.