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;
Pension term assurance effectively stopped any more new PTA business being written. Those with existing policies were allowed to keep them running. Despite what the name might suggest, Pension Term Assurance did not have to form part of a pension - it merely needed to be taken out at the same time as a new pension was set up. Pension term assurance Pension Term Assurance (PTA) was a form of life insurance available within the United Kingdom. Although PTA had been available for several years, it only became mainstream when changes were made to pension legislation on "A Day", 6 April 2006. Following