# Contrast

How much brighter an object is than the sky around it — the key to seeing faint things.

Faint nebulae and galaxies are only a little brighter than the sky behind them. Anything that darkens the background — a darker site, the Moon down, a filter that blocks skyglow, the right magnification — raises their contrast and makes them easier to see.

**Related:** [Surface brightness](https://astropilot.space/glossary/surface-brightness.md), [Light pollution](https://astropilot.space/glossary/light-pollution.md), [Nebula filter](https://astropilot.space/glossary/nebula-filter.md), [Exit pupil](https://astropilot.space/glossary/exit-pupil.md)

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