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:
“My country is bleeding, my people are perishing around me. But I feel as a South Carolinian, I am bound to tell the North, go on! go on! Never falter, never abandon the principles which you have adopted.”
—Angelina Grimké (1805–1879)
“I cannot consent that my mortal body shall be laid in a repository prepared for an Emperor or a King—my republican feelings and principles forbid it—the simplicity of our system of government forbids it.”
—Andrew Jackson (1767–1845)
“A bureaucracy is sure to think that its duty is to augment official power, official business, or official members, rather than to leave free the energies of mankind; it overdoes the quantity of government, as well as impairs its quality. The truth is, that a skilled bureaucracy ... is, though it boasts of an appearance of science, quite inconsistent with the true principles of the art of business.”
—Walter Bagehot (1826–1877)