A telescope that uses as its primary optical element a lens. Binoculars are a type of refractor. In general, refractors are much more expensive to build and buy than are ...
A telescope that uses as its primary optical element a mirror. Nearly all large telescopes in use today by amateur and professional astronomers are reflecting telescopes.
In astronomy, the measurement of the light emitting from astronomical objects, generally in the visible or infrared bands, in which a specific or general wavelength band is ...
The apparent displacement or the difference in apparent direction of an object as seen from two different points not on a straight line with the object (as from two different ...
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