Spiral Galaxy

space · galaxies · cosmic structure · super big

Cosmic pinwheel shape. Spiral galaxies have beautiful arms that curve outward like a pinwheel, all spinning around a dense center called the bulge. It's like the entire galaxy is slowly rotating in space.

Made of three parts. Every spiral galaxy has a flat, rotating disk full of stars and cosmic dust, a bright central bulge packed with stars, and a fainter halo of stars surrounding the whole thing.

Edwin Hubble's discovery. Astronomer Edwin Hubble first described spiral galaxies in 1936 and created a special way to sort and study different types of galaxies, which scientists still use today.

Surrounded by star clusters. Many spiral galaxies are wrapped in a faint outer halo containing globular clusters, ancient, tightly packed groups of thousands of stars orbiting the main galaxy.