Sun's galactic orbit
We are used to the idea that Earth orbits the Sun once a year. But the Sun is not standing still — it is itself a star in a giant rotating galaxy, swept along on a long, slow circuit around the galactic center, carrying Earth and the whole Solar System with it. Just as the planets follow the Sun, the Sun follows the Milky Way. The Sun's galactic orbit is this grand journey: our star's path as it sails around the heart of the galaxy.
The Sun sits roughly 26,000 light-years from the galactic center, out in the disk, and it orbits at about 220 to 230 kilometers per second — fast enough to cross the distance from the Earth to the Moon in under half an hour. Even at that blistering speed the galaxy is so enormous that one full lap takes about 220 to 250 million years, a span sometimes called a 'galactic year' or cosmic year. The Sun has completed only about 20 such laps in its whole 4.6-billion-year life. Its orbit is not a perfect circle: the Sun also bobs gently up and down through the disk's midplane every few tens of millions of years, and drifts slightly in and out.
The Sun's galactic orbit matters because it sets our long-term cosmic environment. The orbital speed at our distance is a key data point on the rotation curve, helping reveal the galaxy's hidden mass. The journey also carries the Solar System through changing surroundings — denser regions, spiral arms, and gas clouds — which some researchers have speculated might subtly influence the planet over geological time, though such links are uncertain and debated. A useful correction to intuition: the Sun does not orbit because the central black hole holds it. It orbits the combined mass of everything inside its path — billions of stars, gas, and especially dark matter — of which the central black hole is only a tiny fraction.
The last time the Sun was at its current point in its galactic orbit, dinosaurs had not yet evolved — one galactic year ago, the Earth was in the Permian period, before the largest mass extinction in its history. We have circled the galaxy only about 20 times since the Sun was born.
One galactic year is about 230 million years; the Sun has lived only about 20 of them.
The Sun orbits the galaxy's total enclosed mass — mostly stars and dark matter — not the central black hole, which contributes a negligible share of the gravity at our distance.