Free Astronomy Magazine November-December 2026

43 NOVEMBER-DECEMBER 2026 ASTRO PUBLISHING biting our galaxy’s cen- tral black hole, Sagittar- ius A*, have led to this breakthrough discovery of a very promising star. Because it orbits so close to Sagittarius A*, S301 opens a new win- dow to the fundamen- tal properties of space- time in this extreme black-hole environ- ment,” says Nobel Prize winner Reinhard Gen- zel, Director at the Max Planck Institute for Ex- traterrestrial Physics (MPE) in Garching, Ger- many, and founding member of the collabo- ration that made the new observations. “What is special about this star is that it’s orbit- ing Sagittarius A* on a very tight orbit, taking just 8.7 years to com- plete it, and is ap- proaching the black hole at a mere 12 times the distance of Earth to the Sun. That is un- precedented,” says Felix Mang, PhD student at MPE and author of the study published in Na- ture . During its closest pas- sage to the black hole, the star travels at a- round 25,000 kilome- tres per second — 100,000 times faster than a commercial plane, or over 8% of the speed of light — making it the record holder for the fastest star in the Milky Way. S301 also comes closer to Sagittarius A* than any other star observed so far, approach- ing the black hole at around the dis- tance of Saturn to the Sun. Because S301 comes so close to Sagittarius A*, it is the first star known that could be used to directly measure the rotation of a black hole. Like most things in our Universe, as- tronomers predict that Sagittarius A* spins. According to Einstein’s gen- eral theory of relativity, a spinning black hole drags spacetime along with it and twists it, which impacts the orbits of surrounding stars. The effect is felt more strongly for ob- jects orbiting fast-rotating black holes at close range. T his sequence of images, taken with the GRAVITY instrument at ESO’s Very Large Telescope Interferometer (VLTI), shows several stars orbiting Sagittarius A*, the supermassive black hole at the centre of our galaxy. These stars are collectively known as S-stars. The arrows in these images indicate their observed motion around the black hole. One of the stars, S301, was recently found to pass much closer to the black hole than the other S-stars. Its orbit is shown here with an elliptical curve. In each frame, the solid curve shows the path that the star has al- ready completed up to that point, whereas the dashed one marks the path it will follow after- wards. [ESO/GRAVITY collaboration]