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postal service
(Encyclopedia)postal service, arrangements made by a government for the transmission of letters, packages, and periodicals, and for related services. Early courier systems for government use were organized in the P...sidereal period
(Encyclopedia)sidereal period, in astronomy, length of time a body takes to complete an orbit relative to the fixed stars. See sidereal time. ...year
(Encyclopedia)year, time required for the earth to complete one orbit about the sun. The solar or tropical year is measured relative to the sun and is equal to 365 days, 5 hr, 48 min, 46 sec of mean solar time (see...horology
(Encyclopedia)horology hōrŏlˈəjē [key], science of measuring time and technology of constructing instruments for its measurement or recording. Early measurements of the passage of time were based on observatio...Neoplatonism
(Encyclopedia)Neoplatonism nēˌōplāˈtənĭzəm [key], ancient mystical philosophy based on the doctrines of Plato. Neoplatonism was an early influence on Christian thinkers. The Christian apologists Clement...sidereal year
(Encyclopedia)sidereal year, time required for the earth to complete an orbit of the sun relative to the stars. The sidereal year is 365 days, 6 hr, 9 min, 9.5 sec of mean solar time (see solar time). It is 20 min ...day
(Encyclopedia)day, period of time for the earth to rotate once on its axis. The ordinary day, or solar day, is measured relative to the sun, being the time between successive passages of the sun over a stationary o...geologic timescale
(Encyclopedia) CE5 geologic timescale, a chronological scale of earth's history used to measure the relative or absolute age of any part of geologic time. Of the numerous timescales, the most common is based on g...second
(Encyclopedia)second, abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the da...Janus, in Roman religion
(Encyclopedia)Janus jāˈnəs [key], in Roman religion, god of beginnings. He was one of the principal Roman gods, the custodian of the universe. The first hour of the day, the first day of the month, the first mon...Browse by Subject
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