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;
Singular term pronouns (e.g. "she"), demonstrative pronouns (e.g. "this"), etc. Historically, various definitions for "singular term" have been offered: Singular term A singular term is a paradigmatic referring device in a language. Singular terms are of philosophical importance for philosophers of language, because they "refer" to things in the world, and the ability of words to refer calls for scrutiny. Singular terms are defined as expressions that purport to denote or designate particular individual people, places, or other objects. They contrast with "general terms" (such as "car" or "chair") which can apply to more than one thing. There are various kinds of