Why Is Everything in Space Always Moving?

Everything in the universe is constantly in motion, from planets orbiting stars to galaxies moving through space. This perpetual movement can be traced back to the very beginning—the Big Bang. Astrophysicists like Edward Gomez explain that the universe started expanding outward from an infinitely dense point, causing everything to move apart from the moment of its creation.

“The beginning was movement,” says Carol Christian, an astrophysicist with the Hubble Space Telescope. This initial expansion set everything in motion, and that movement has been built into the universe ever since. While the universe’s expansion mainly affects objects that are far apart, motion on smaller scales—like rotation and orbit—is driven by angular momentum.

Angular momentum is why planets orbit the sun and why stars and galaxies spin. It’s a phenomenon that occurs when two objects in space influence each other gravitationally, causing them to move in circular orbits instead of colliding. This effect is fundamental to the formation of structures in space, from solar systems to galaxies.

Interestingly, galaxies don’t spin in the way we’d expect based solely on visible matter. The outer stars should rotate slower than those near the center, but they don’t—suggesting the presence of dark matter, an invisible substance that interacts gravitationally and experiences angular momentum, further contributing to the motion we observe in space.

In essence, motion is a fundamental part of the universe, showing that it is alive with ongoing chemical and physical reactions that require energy—the most basic form of which is motion.