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:
“Our national determination to keep free of foreign wars and foreign entanglements cannot prevent us from feeling deep concern when ideals and principles that we have cherished are challenged.”
—Franklin D. Roosevelt (1882–1945)
“I have ever deemed it fundamental for the United States never to take active part in the quarrels of Europe. Their political interests are entirely distinct from ours. Their mutual jealousies, their balance of power, their complicated alliances, their forms and principles of government, are all foreign to us. They are nations of eternal war.”
—Thomas Jefferson (1743–1826)
“With our principles we seek to rule our habits with an iron hand, or to justify, honor, scold, or conceal them:Mtwo men with identical principles are likely to be seeking fundamentally different things with them.”
—Friedrich Nietzsche (1844–1900)