Astronomers discover S301, a star orbiting close to Milky Way's central black hole

The short version

• Astronomers announced the discovery of S301, a star on an 8.7-year orbit that takes it closer to the Milky Way's supermassive black hole than any previously known star.
• At its closest approach, S301 travels at 90 million kilometers per hour, or roughly 8% the speed of light.
• The extreme speed and intense gravity generate significant relativistic effects, including time dilation, optical aberration, and severe Doppler shifts.
• Astronomers suspect even closer, fainter stars may remain hidden within the dense dust at the galactic center.

Key facts

• Astronomers announced the discovery of S301 in August 2026, identifying it as a star that approaches within roughly 1.7 billion kilometers of Sagittarius A*.[Scientific American]
• S301's closest orbital approach surpasses the record previously held by the star S2, which reached 18 billion kilometers from the supermassive black hole.[Scientific American]
• At perigalacticon, S301 reaches a velocity of 90 million kilometers per hour, corresponding to 8% of the speed of light.[Scientific American]
• The star completes its highly elliptical orbit around the galactic center every 8.7 Earth years.[Scientific American]
• Due to time dilation at maximum orbital speed, a clock near S301 would lose approximately 11 seconds per hour relative to an observer on Earth.[Scientific American]

Sources

Outlet counts describe coverage, not independent confirmation. Reports may share a wire service or original source.

• This star has the strangest sky in the galaxyScientific American metered