Astronomers Discover S301, Fastest Star Orbiting Milky Way's Black Hole

Astronomers have long tracked stars near the center of the Milky Way, searching for clues about the massive black hole, Sagittarius A*, lurking there. These stars, known as S-stars, move in tight, fast orbits, providing a natural laboratory for extreme physics.

The hunt for even faster and closer stars continued as telescopes and instruments improved. Researchers hoped to find a star whose speed and proximity could reveal more about the black hole's properties and the nature of gravity itself.

In August 2026, several research teams announced the discovery of S301, a star orbiting Sagittarius A* at a record-breaking speed. According to Science Magazine and Live Science, S301 moves at about 25,000 kilometers per second, or more than 8 percent the speed of light. Live Science reported that the star completes an orbit every 8.7 years, making it both the fastest and closest known star to the black hole.

Phys.org and World News CNA highlighted that S301's orbit is so tight and fast that it offers a rare opportunity to study the effects of the black hole's spin on nearby objects. Scientists believe this could allow them to directly measure Sagittarius A*'s rotation for the first time within the next decade.

Coverage from outlets like Scientific American and Universe Today noted that the discovery also provides a new way to test Einstein's theory of general relativity under extreme conditions. The Gravity collaboration, whose findings appeared in Nature, played a key role in pinpointing S301's speed and orbit, according to ANSA.it.

Further details emerged in follow-up reports. For instance, Ars Technica pointed out that S301's nearly escape-velocity orbit (with an eccentricity of 0.9832) makes it especially useful for probing the black hole's gravitational field. In.gr added that S301 is about 1.5 times as massive as the Sun and five times brighter, making it stand out among stars near the galactic center.

S301 is now recognized as the fastest known star in the Milky Way, moving at incredible speeds around the supermassive black hole Sagittarius A*. Its orbit and behavior are already providing astronomers with new data on how gravity and black holes work in the most extreme environments.

The discovery has been widely reported and discussed in the scientific community, with researchers now focused on monitoring S301's future orbits and interactions with the black hole.

Scientists plan to use S301's future movements to attempt the first direct measurement of Sagittarius A*'s spin. Continued observation will also allow researchers to test general relativity and look for any deviations from Einstein's predictions. The next few years are expected to bring more precise data as S301 completes its tight, high-speed loop around the black hole.