Galactic means anything related to a galaxy, which is an enormous system of billions of stars, along with planets, dust, and gas, all held together by gravity. Our own galaxy, the Milky Way, contains hundreds of billions of stars, including our sun.

When astronomers talk about galactic distances, they mean the vast spaces between stars within a galaxy, measured in light-years (the distance light travels in a year). When scientists study galaxy formation, they're investigating how galaxies came to exist and how they change over millions of years.

The word often appears in science fiction: Star Wars takes place in a galaxy far, far away, with galactic empires spanning countless star systems. But galactic also describes real scientific phenomena. A galactic core is the bright center of a galaxy, often containing a supermassive black hole. Galaxy clusters are groups of galaxies held together by gravity.

Sometimes people use galactic more casually to mean “enormous” or “mind-bogglingly huge,” like calling a mistake a galactic blunder. This usage captures how the word makes us think of scales almost too large to imagine, where distances are so vast that even light takes years to cross them.