Understanding Galaxies
The extragalactic universe — the forms of galaxies, the active nuclei at their hearts, how they evolve, and the great structures they build. Built on real galaxies and object classes; nothing is fabricated.
Related entities
- Galaxy morphology
Spiral Galaxy
A flattened, rotating disk of stars, gas, and dust wound into spiral arms, with a central bulge. The arms are where new stars form, tracing waves of star formation sweeping through the disk.
- AGN type
Radio Galaxy
A galaxy — usually a giant elliptical — that pours enormous energy into twin jets and lobes of radio-emitting plasma, launched by its central black hole and reaching far beyond the visible galaxy. Centaurus A is the nearest.
- Galactic process
Galaxy Merger
The collision and coalescence of two galaxies. Mergers trigger bursts of star formation, funnel gas to the central black hole, and can turn two spirals into a single elliptical — a driving force of galaxy evolution.
- Cosmic structure
The Local Group
The gravitationally-bound group of galaxies the Milky Way belongs to — dominated by the Milky Way and Andromeda, with the Triangulum galaxy and dozens of dwarfs. Andromeda and the Milky Way are approaching, and will merge in a few billion years.