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Astronomy 2e

Key Terms

Astronomy 2eKey Terms
adaptive optics
systems used with telescopes that can compensate for distortions in an image introduced by the atmosphere, thus resulting in sharper images
aperture
diameter of the primary lens or mirror of a telescope
charge-coupled device (CCD)
array of high-sensitivity electronic detectors of electromagnetic radiation, used at the focus of a telescope (or camera lens) to record an image or spectrum
chromatic aberration
distortion that causes an image to appear fuzzy when each wavelength coming into a transparent material focuses at a different spot
detector
device sensitive to electromagnetic radiation that makes a record of astronomical observations
eyepiece
magnifying lens used to view the image produced by the objective lens or primary mirror of a telescope
focus
(of telescope) point where the rays of light converged by a mirror or lens meet
interference
process in which waves mix together such that their crests and troughs can alternately reinforce and cancel one another
interferometer
instrument that combines electromagnetic radiation from one or more telescopes to obtain a resolution equivalent to what would be obtained with a single telescope with a diameter equal to the baseline separating the individual separate telescopes
interferometer array
combination of multiple radio dishes to, in effect, work like a large number of two-dish interferometers
prime focus
point in a telescope where the objective lens or primary mirror focuses the light
radar
technique of transmitting radio waves to an object and then detecting the radiation that the object reflects back to the transmitter; used to measure the distance to, and motion of, a target object or to form images of it
reflecting telescope
telescope in which the principal light collector is a concave mirror
refracting telescope
telescope in which the principal light collector is a lens or system of lenses
resolution
detail in an image; specifically, the smallest angular (or linear) features that can be distinguished
seeing
unsteadiness of Earth’s atmosphere, which blurs telescopic images; good seeing means the atmosphere is steady
telescope
instrument for collecting visible-light or other electromagnetic radiation
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