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;
Term life insurance basis over a specific period of time. Term life insurance can be contrasted to permanent life insurance such as whole life, universal life, and variable universal life, which guarantee coverage at fixed premiums for the lifetime of the covered individual unless the policy is allowed to lapse. Term insurance is not generally used for estate planning needs or charitable giving strategies but is used for pure income replacement needs for an individual. Term insurance functions in a manner similar to most other types of insurance in that it satisfies claims against what is insured if the premiums are up to