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:
“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)
“The same principles which at first view lead to skepticism, pursued to a certain point, bring men back to common sense.”
—George Berkeley (1685–1753)
“Prohibition will work great injury to the cause of temperance. It is a species of intemperance within itself, for it goes beyond the bounds of reason in that it attempts to control a man’s appetite by legislation, and makes a crime out of things that are not crimes. A Prohibition law strikes a blow at the very principles upon which our government was founded.”
—Abraham Lincoln (1809–1865)