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.
Famous quotes containing the words celestial and/or sphere:
“Your enjoyment of the world is never right, till every morning you awake in Heaven: see yourself in your Fathers palace; and look upon the skies, the earth, and the air as celestial joys: having such a reverend esteem of all, as if you were among the angels.”
—Thomas Traherne (16361674)
“Thought dissolves the material universe by carrying the mind up into a sphere where all is plastic.”
—Ralph Waldo Emerson (18031882)