Cheryl Scheffer

Sea turtle hatchlings begin their solitary transoceanic migration.

This is how the Solar System travels around the center of the galaxy, taking 225 million to 250 million years for a full orbit.

The Sun has only 22 galactic orbits left. Earth races around the Sun at ~67,000 mph (107,000 km/h), giving us our familiar 365.25-day year and changing seasons. But the Sun is in motion too, hurtling through the Milky Way at ~514,000 mph (828,000 km/h) on a grand orbit around the galactic center. One complete lap, known as a cosmic year, takes roughly 225–230 million years. When the Sun finished its most recent galactic orbit, the earliest dinosaurs were just beginning to roam Earth. Since its birth ~4.6 billion years ago, our star has completed about 20 such orbits. Stellar models predict the Sun will keep fusing hydrogen in its core for another ~5 billion years before it swells into a red giant and eventually fades into a white dwarf. At its current orbital speed, that leaves roughly 22 more laps around the Milky Way. Each cosmic year sweeps the entire Solar System tens of thousands of light-years across the galaxy, through dense spiral arms rich with star-forming regions, past ancient globular clusters, and amid countless other stars. Continents drift, mountains rise and erode, entire species evolve and vanish, all within a tiny fraction of one galactic circuit. Human civilization, from the first cities to today’s digital age, has existed for less than 0.001% of a single cosmic year. We are passengers on a star halfway through its ~10-billion-year galactic journey across a 100,000-light-year-wide disk, witnessing just the briefest sliver of one ongoing lap in an unimaginably vast cosmic dance.