We live on a planet that seems motionless, yet Earth orbits the Sun at a dizzying speed, and our entire Solar System moves through the galaxy. But how fast exactly are we traveling through the cosmos?

The universe is supposed to look the same no matter where you stand. That idea, known as the cosmological principle, sits at the heart of modern astrophysics. It says matter spreads out evenly when ...

The workings of our solar system are roughly the same now as they have been for millions of years. Moons circle their planets, the planets circle the sun, the sun’s magnetic fields and sunspots wax ...