Geocentric model the coordinate system in order to predict the motions of planetary bodies, though doing so may make calculations easier to perform or interpret. A geocentric coordinate system can be more convenient when dealing only with bodies mostly influenced by the gravity of the Earth (such as artificial satellites and the Moon), or when calculating what the sky will look like when viewed from Earth (as opposed to an imaginary observer looking down on the entire solar system, where a different coordinate system might be more convenient). The Ptolemaic model of the solar system held sway into the early modern age;
Iron Mountain Central Historic District Iron Mountain Central Historic District The Iron Mountain Central Historic District is a historic district, broadly located between Fleshiem and C Streets and between Iron Mountain and Stockbridge Avenues in Iron Mountain, Michigan. The district covers the city's central business district and adjacent areas. It is primarily commercial, but also contains the historic county courthouse complex, and school, library, and church buildings. It was listed on the National Register of Historic Places in 2013. Lake Superior Iron Ranges]] A major iron ore deposit was discovered near what is now Iron Mountain in 1878/79; the first ore from the first area