Principles
For detailed information on specific designs of reflecting, refracting, and catadioptric telescopes: see the main articles on Reflecting telescopes, Refracting telescopes, and Catadioptrics.
The basic scheme is that the primary light-gathering element the objective (1) (the convex lens or concave mirror used to gather the incoming light), focuses that light from the distant object (4) to a focal plane where it forms a real image (5). This image may be recorded or viewed through an eyepiece (2) which acts like a magnifying glass. The eye (3) then sees an inverted magnified virtual image (6) of the object.
Read more about this topic: Optical Telescope
Famous quotes containing the word principles:
“All those who write either explicitly or by insinuation against the dignity, freedom, and immortality of the human soul, may so far forth be justly said to unhinge the principles of morality, and destroy the means of making men reasonably virtuous.”
—George Berkeley (1685–1753)
“The chief lesson of the Depression should never be forgotten. Even our liberty-loving American people will sacrifice their freedom and their democratic principles if their security and their very lives are threatened by another breakdown of our free enterprise system. We can no more afford another general depression than we can afford another total war, if democracy is to survive.”
—Agnes E. Meyer (1887–1970)
“It must appear impossible, that theism could, from reasoning, have been the primary religion of human race, and have afterwards, by its corruption, given birth to polytheism and to all the various superstitions of the heathen world. Reason, when obvious, prevents these corruptions: When abstruse, it keeps the principles entirely from the knowledge of the vulgar, who are alone liable to corrupt any principle or opinion.
”
—David Hume (1711–1776)