Meet S301, the Milky Way's Fastest Star Racing Around Our Galaxy's Black Hole

A Record-Breaking Star Born From Cosmic Chaos

Scientists have detected the fastest-known star in the Milky Way — a stellar speedster zooming around the supermassive black hole at the center of our galaxy that might hold the key to measuring the spin of this celestial beast for the very first time. The discovery, published on August 19, 2026, is already reshaping what astronomers thought they knew about the extreme environment at our galaxy's core.

The star, named S301, is around 50% more massive and five times brighter than our sun, traveling at speeds up to about 56 million miles per hour — more than 8% the speed of light. No other star in our galaxy or elsewhere has ever been clocked at that speed. To put that in perspective, a commercial airplane cruises at roughly 575 mph. S301 is moving about 100,000 times faster.

S301's orbital properties, and the fact that stars cannot form so close to a massive black hole, indicate that the star was likely part of a binary pair that was torn apart by the tidal forces of Sagittarius A*. In the process, S301 became trapped by the black hole's gravity while its companion star was kicked out with high velocity, most likely enough to leave the galaxy altogether. It's a violent origin story befitting one of the universe's most extreme environments.

Closer Than Any Star Before It

S301 travels in a highly elliptical path around Sagittarius A*, taking about 8.7 years to complete one full orbit. It comes within roughly 136 Schwarzschild radii of Sagittarius A* — about 10 times closer to the black hole than S2, the previous record-holding star and one of the best-studied objects near the galactic center. That staggering proximity is what makes this star so scientifically valuable.

Researchers used the European Southern Observatory's Very Large Telescope Interferometer in Chile's Atacama Desert to study the star. The facility combines the light collected by four eight-meter telescopes, allowing astronomers to observe the crowded region around the black hole with exceptional precision. Researchers spotted S301 in 2023, then traced it back through observations from 2021 and 2017.

A Key to Unlocking Einstein's Theory

Nobel Prize winner Reinhard Genzel, Director at the Max Planck Institute for Extraterrestrial Physics, called it a "breakthrough discovery," noting that "because it orbits so close to Sagittarius A*, S301 opens a new window to the fundamental properties of spacetime in this extreme black-hole environment." The implications go beyond a speed record — they touch on some of the deepest questions in physics.

Study co-author Stefan Gillessen of the Max Planck Institute explained: "For the first time, we would actually be able to measure very directly the spin of a massive black hole, which would be a key test of Einstein's theory." The extreme orbit could turn S301 into a powerful tool for testing some of the most challenging predictions of Einstein's theory of relativity. Measuring a black hole's spin has long been considered one of astrophysics' most elusive goals — and S301 may finally make it achievable.

What Comes Next

Scientists were able to trace S301's orbital history back to 2017, finding that it last made its closest approach to the central black hole in early 2023. Follow-up observations with GRAVITY+ and with the MICADO instrument on ESO's upcoming Extremely Large Telescope will be crucial for tracing S301's path over the next decade, as it makes its next closest passage in 2031.

Observing at least two complete orbits of S301 would allow its trajectory to be constrained with sufficient precision to enable the team to directly determine the spin of Sagittarius A* for the first time. While Sagittarius A* is presently in a quiescent state, its gravitational pull is considerable — but researchers say S301 should remain safe from the black hole's pull. For now, the star continues its ancient, breakneck journey around one of the most powerful objects in the known universe — and with each lap, it carries the promise of answering questions humanity has wondered about for generations.