# Deep-sky object

Also called: DSO, deep sky.

Anything in the night sky beyond the Solar System that isn't a single star: star clusters, nebulae and galaxies.

Deep-sky objects are the faint, fuzzy treasures of the sky: [open](https://astropilot.space/glossary/open-cluster) and [globular clusters](https://astropilot.space/glossary/globular-cluster), [nebulae](https://astropilot.space/glossary/nebula) and [galaxies](https://astropilot.space/glossary/galaxy). Most are far too faint to see without optical help, and many look like soft grey glows rather than the colourful pictures in books.

Observers usually count [double stars](https://astropilot.space/glossary/double-star) among them too, and catalogs such as the [messier catalog](https://astropilot.space/glossary/messier-catalog) and the [NGC](https://astropilot.space/glossary/ngc-ic) are made almost entirely of them.

**At the eyepiece:** Deep-sky objects reward a dark sky, a dark-adapted eye and patience more than magnification: see [dark adaptation](https://astropilot.space/glossary/dark-adaptation) and [averted vision](https://astropilot.space/glossary/averted-vision).

**In AstroPilot:** Explore lists every deep-sky object in AstroPilot's catalog, ranked for your sky, your instrument and tonight's Moon.

**Examples:** [M31](https://astropilot.space/object/M31.md), [M13](https://astropilot.space/object/M13.md), [M42](https://astropilot.space/object/M42.md), [M57](https://astropilot.space/object/M57.md)

**Related:** [Galaxy](https://astropilot.space/glossary/galaxy.md), [Nebula](https://astropilot.space/glossary/nebula.md), [Open cluster](https://astropilot.space/glossary/open-cluster.md), [Globular cluster](https://astropilot.space/glossary/globular-cluster.md), [Messier catalog](https://astropilot.space/glossary/messier-catalog.md)

From the AstroPilot astronomy glossary: https://astropilot.space/glossary/deep-sky-object