The Celestial Map

We live on a planet that orbits the Sun, one of two hundred billion stars in the Milky Way galaxy, where the visible night stars belong to our galaxy and orbit a distant center within a flattened disk that also contains the Sun, far from that center. Moving at 500,000 miles per hour, the Sun takes about 200 million years to complete one orbit of the galaxy. A celestial map plots the positions of the stars at noon, April 22, 1979, and includes not only stars visible to the naked eye but also the Sun, Mercury, Venus, and Mars in their appropriate phases, four asteroids or minor planets—Ceres, Pallas, Juno, and Vesta—and other objects of particular interest in the galaxy, including variable stars, double stars, spectroscopic binaries, globular clusters, open clusters, and pulsars. It also shows the faintly etched region called the Milky Way, the combined light of stars seen through the disk of our galaxy. Astronomers have known for almost 100 years that our galaxy is one of billions and billions of galaxies in the universe, each containing vast numbers of stars. The closest large spiral neighboring galaxy visible to us is the Andromeda galaxy, also M31, and five other galaxies are included as well, one of them M33 near M31. Also indicated are ten quasars, enormously bright nuclei of very distant galaxies that astronomers speculate may be exotic massive nuclear black holes swallowing some of the stars in their galaxies. The map identifies more than 2,700 stars with stainless steel studs of different sizes from faintest to brightest, and uses lines of right ascension at 15 degree intervals and circles of declination at 30-degree intervals to form a grid fixing the sky positions of celestial objects. Measuring 28 feet in diameter, it depicts 55 percent of the entire sky.

Washington, District of Columbia · United States