Right at the heart of our home galaxy, the Milky Way, sits a monster: a supermassive black hole called Sagittarius A* (pronounced “A-star”). It contains roughly 4 million times the mass of our Sun, all crammed into a region smaller than our solar system. We orbit it from 26,000 light-years away.
For decades, astronomers strongly suspected Sgr A* was there, based on watching stars near the center of the galaxy whip around an invisible something at high speed. The orbits could only be explained by an enormous concentration of mass. In 2022, the Event Horizon Telescope released the first actual photograph of it - a dark circle ringed by hot glowing gas, just like the one taken of the M87 black hole three years earlier.
Almost every large galaxy seems to have a similar monster at its center, and astronomers are still figuring out exactly why. The black hole likely grew alongside the galaxy itself, eating stars and gas over billions of years. Don’t worry, though: Sgr A* is way too far away to suck us in. From here, it’s just a quiet anchor at the center of our spiral.
