Telescopy - Glossary of Terms

There are lots of big words in telescopy, and the broader realm of Astronomy
in general. Herein you will find the definitions for all the different
multisyllabic words I use in my series on telescopy!

  • Angular Resolution is the minimum distance required between two objects in order for an optical device to distinguish them as separate. Related to Resolving Power.
  • Aperture
  • Astigmatism
  • Catadioptric
  • Catoptric
  • Chromatic Aberration
  • Coma
  • Dioptric
  • Distortion
  • Field Curvature
  • Focal Length
  • Focal Ratio
  • Lens Sag
  • Mirror Sag
  • Objective: The lens at the front end of a dioptric system, or the large primary mirror of a catoptric or catadioptric system. Light-gathering power and image resolution increases with the size of the objective.
  • Reflective (see Catoptric)
  • Refractive (see Dioptric)
  • Resolving Power is the ability of a device to separate two objects that are located far from the device but close together.
  • Spherical Aberration