Observing equipment
Astronomical Filter
A filter that blocks unwanted light — the orange glow of light pollution, or all but a single emission line such as hydrogen-alpha — so that faint nebulae stand out against the background. Filters let observers under city skies see what would otherwise be washed out.
Methods, objects & tools
Knowledge connections
- Associated withCamera
- Associated withNarrowband Imaging
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.