# Galaxy

A vast system of billions of stars, gas and dust, held together by gravity — our own is the Milky Way.

Every star you see with the naked eye belongs to our own galaxy, the [milky way](https://astropilot.space/glossary/milky-way). Beyond it lie billions of others, from tiny dwarfs to giants of a trillion stars. The nearest large one, the Andromeda Galaxy (M 31), is about 2.5 million [light-years](https://astropilot.space/glossary/light-year) away — the most distant thing you can see without optics.

Through a telescope most galaxies are soft oval glows with a brighter core. Spiral arms and [dust lanes](https://astropilot.space/glossary/edge-on-galaxy) need a dark sky, a bigger [aperture](https://astropilot.space/glossary/aperture) and some practice. Astronomers sort them by shape: [spirals](https://astropilot.space/glossary/spiral-galaxy), [ellipticals](https://astropilot.space/glossary/elliptical-galaxy), lenticulars and irregulars (see [hubble type](https://astropilot.space/glossary/hubble-type)).

**At the eyepiece:** Galaxies are hurt most by [light pollution](https://astropilot.space/glossary/light-pollution) and moonlight. Use medium power (a 2–3 mm [exit pupil](https://astropilot.space/glossary/exit-pupil)) and no nebula filter — galaxies shine in starlight, which those filters block.

**Examples:** [M31](https://astropilot.space/object/M31.md), [M51](https://astropilot.space/object/M51.md), [M81](https://astropilot.space/object/M81.md), [M104](https://astropilot.space/object/M104.md)

**Related:** [Spiral galaxy](https://astropilot.space/glossary/spiral-galaxy.md), [Elliptical galaxy](https://astropilot.space/glossary/elliptical-galaxy.md), [Edge-on galaxy](https://astropilot.space/glossary/edge-on-galaxy.md), [Galaxy group & cluster](https://astropilot.space/glossary/galaxy-group.md), [Surface brightness](https://astropilot.space/glossary/surface-brightness.md), [Milky Way](https://astropilot.space/glossary/milky-way.md)

From the AstroPilot astronomy glossary: https://astropilot.space/glossary/galaxy