Star S301’s Close Orbit Around Sagittarius A* Produces Unprecedented Sky Effects

In August 2026, researchers announced the discovery of star S301, which follows a highly elongated orbit that brings it as close as 1.7 billion km to the supermassive black hole Sagittarius A* at the Milky Way’s core. At pericenter the star travels at roughly 90 million km per hour, about eight percent of light speed, causing pronounced relativistic Doppler shifts that tint hydrogen clouds orange when approaching and deeper red when receding.

The black-hole’s shadow spans more than a degree across S301’s sky, dwarfing Earth’s full moon, while the surrounding accretion ring would appear about four degrees wide. Light-aberration shifts star positions by up to nine degrees, making constellations appear to move over the star’s 8.7-year orbit. Time runs slower on S301, with clocks losing about 11 seconds per hour compared to Earth. Intense X-ray outbursts from the black hole would render the region hostile to any nearby planets, which are also unlikely to survive the star’s own heat.