Precession of the Equinoxes Classical & Historical Planisphere (Southern Hemisphere) A special planisphere made specifically for the southern hemisphere. This planisphere created by Dr. Milton D. Heifetz, author of A Walk through the Heavens: A Guide to the Stars and Constellations and their Legends, shows which stars are visible at any hour, day or month, thousands of years in the past, the present and thousands of years into the future. This unique astronomical device illustrates precession in a way that can otherwise only be duplicated by using a computer and planetarium. It also demonstrates the change in declination over the millennia and which star will be the North Star in the future. Use the Historical Planisphere to help demonstrate the following facts: The earth orbits around the sun on a plane called the ecliptic. Because of the earth's tilt, twice per year the earth's equatorial plane intersects the ecliptic plane. That time of intersection is called the equinox. In about 130 B.C., the Greek astronomer Hipparchus noticed a change in the position of the stars. Due to a wobble of the earth as it spins on its axis, the poles of the earth trace a circle in the sky that alters the position of the north and south celestial poles and the celestial equator. As a result, the equinox slowly changes its position along the ecliptic. This is called precession of the equinoxes.10” diameter, 30-40 degrees S. Latitude.