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:
“The stillness was intense and almost conscious, as if it were a natural Sabbath, and we fancied that the morning was the evening of a celestial day.”
—Henry David Thoreau (1817–1862)
“If today there is a proper American “sphere of influence” it is this fragile sphere called earth upon which all men live and share a common fate—a sphere where our influence must be for peace and justice.”
—Hubert H. Humphrey (1911–1978)