Astronomy: Chapter 6
Chromatic Aberration
A distortion found in refracting telescopes because lenses focus different colors at slightly different distances. Images are consequently surrounded by color fringes.
Seeing
Atmospheric conditions on a given night. When the atmosphere is unsteady, producing blurred images, the seeing is said to be poor.
Diffraction Fringe
Blurred fringe surrounding any image caused by the wave properties of light. Because of this, no image detail smaller than the fringe can be seen.
Adaptive Optics
computer-controlled telescope mirrors that can at least partially compensate for seeing
Active Optics
optical elements whose position or shape is continuously controlled by computers
Light Gathering Power
the ability of a telescope to collect light, proportional to the area of the telescope's objective lens or mirror
Resolving Power
the ability of a telescope to reveal fine detail; depends on the diameter of the telescope objective
Focal Length
the distance from a lens to the point where it focuses parallel rays of light
Light Pollution
the illumination of the night sky by waste light from cities and outdoor lighting, which prevents the observation of faint objects
Objective Lens/ Mirror
the main optical element in an astronomical telescope. The large lens at the top of the telescope or large mirror at the bottom
Interferometry
the observing technique in which separated telescopes combine to produce a virtual telescope with the resolution of a much larger diameter telescope
Eyepiece
A short-focal-length lens used to enlarge the image in a telescope. The lens nearest the eye.
Refracting Telescope
A telescope that forms images by bending (refracting) light with a lens.
Charge-coupled Device (CCD)
an electronic device consisting of a large array of light-sensitive elements used to record very faint images convert star light into digital material
False Color Image
a representation of graphical data in which the colors are altered or added to reveal details
Reflecting Telescope
a telescope that uses a concave mirror to focus light into an image
