Types of galaxies and how galaxies evolve through mergers

Galaxies come in several main types. Spiral galaxies, like the Milky Way, have a flat disk with spiral arms where gas and dust are still forming new stars. Elliptical galaxies are smooth, rounded, or oval collections of mostly older stars, with little gas left for star formation. Irregular galaxies have no regular shape, and dwarf galaxies are small, faint galaxies that are by far the most common type. Active galaxies have a supermassive black hole at their center pulling in large amounts of matter, which makes their centers extremely bright; the most luminous of these are quasars. Galaxies also evolve by colliding and merging over hundreds of millions of years. Individual stars almost never hit each other, because the space between them is so vast, but the galaxies' gas clouds collide and can trigger bursts of star formation, and the merger of two spirals can build a large elliptical galaxy. The Milky Way is absorbing small dwarf galaxies now, and in several billion years it may have a close encounter and possibly a merger with the Andromeda Galaxy.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report