Geocentric model fire being lighter than air. Beyond the layer of fire, were the solid spheres of aether in which the celestial bodies were embedded. They, themselves, were also entirely composed of aether. Adherence to the geocentric model stemmed largely from several important observations. First of all, if the Earth did move, then one ought to be able to observe the shifting of the fixed stars due to stellar parallax. In short, if the Earth was moving, the shapes of the constellations should change considerably over the course of a year. If they did not appear to move, the stars are either
National Register of Historic Places listings in Central Baltimore National Register of Historic Places listings in Central Baltimore This is a list of National Register of Historic Places properties and districts in downtown Baltimore, Maryland, United States. Many other properties are located in other parts of the city; for these, see National Register of Historic Places listings in Baltimore, Maryland. The locations of the National Register properties and districts listed below (at least for all showing latitude and longitude coordinates below) may be seen in a map by clicking on "Map of all coordinates". Much of the central portion of the city and significant portions of the waterfront and