4 Main Types of Galaxies The Universe holds over 2 trillion galaxies — but astronomers group them into just four main types: Elliptical – Spherical or stretched shapes, full of old stars, almost no new star formation. Spiral – Bright arms swirling around a core. Rich in gas, dust, and young stars. (Like our Milky Way!) Lenticular – A mix between spirals and ellipticals: flat disks, no arms, older stars. Irregular – Chaotic shapes, often warped by collisions, with intense star birth. Classification based on Edwin Hubble’s sequence