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;
Truce term of Schoolchildren". They found truce terms varied according to geographical location, with the exception of "pax". In some places, more than one term was current and often four or five were known, although usually only one term predominated. Schools bordering two linguistic regions honoured both. The words used in urban areas were often at odds with words used in the surrounding countryside. The Opies recorded around 45 truce terms plus variations. The most widely used were "barley", "fainites", "kings", "crosses", "keys", "skinch", "cree" and "scribs". "Barley" was recorded by the Opies as the prevailing term in east Scotland and the