In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the observer. All objects in the observer's sky can be thought of as projected upon the inside surface of the celestial sphere, as if it were the underside of a dome or a hemispherical screen. The celestial sphere is a practical tool for spherical astronomy, allowing observers to plot positions of objects in the sky when their distances are unknown or unimportant.
Read more about Celestial Sphere: Introduction, Celestial Coordinate Systems, History, Star Globe
Famous quotes containing the words celestial and/or sphere:
“I have always endeavored to acquire strict business habits; they are indispensable to every man. If your trade is with the Celestial Empire, then some small counting house on the coast, in some Salem harbor, will be fixture enough.”
—Henry David Thoreau (1817–1862)
“Wherever the State touches the personal life of the infant, the child, the youth, or the aged, helpless, defective in mind, body or moral nature, there the State enters “woman’s peculiar sphere,” her sphere of motherly succor and training, her sphere of sympathetic and self-sacrificing ministration to individual lives.”
—Anna Garlin Spencer (1851–1931)