| Astrophysics (Index) | About |
An occulter is something that blocks light, used in astronomy for some kinds of observation. The term is used for artificial devices that block light from one body to assist in viewing another, examples being a coronagraph, an occulting bar, or a starshade. Coronagraphs often include some optics to assist the process, and the term occulter is sometimes used for the actual internal piece of the coronagraph that actually blocks the unwanted light.
The term occulter could also be used for a celestial body that is usefully blocking part of the celestial sphere, e.g., to make something at a short angular distance observable, or to help determine the exact position of some object.