Civil Time
Related Category: Astronomy: General
local time based on universal time. Civil time may be formally defined as mean solar time plus 12 hr; the civil day begins at midnight, while the mean solar day begins at noon.
civil time
Home ... Science and Technology Astronomy and Space Exploration Astronomy: General ...
Essential reading Compare
side-by-side The Oxford Pocket Dictionary ... A Dictionary of Astronomy The Columbia Encyclopedia, ...
civil time: see Time (types of) civil~.
clinometer: an instrument for measuring the inclination or slope of a surface. Also called an inclinometer.
local civil time (abbr LCT) See local mean time, note. local lunar time The arc of the celestial equator, or the angle at the celestial pole, between the lower branch of the local celestial meridian and the hour circle of the moon, ...
civil time (NASA SP-7, 1965) See mean time, note. civil twilight (NASA SP-7, 1965) See twilight, note. civil year (NASA SP-7, 1965) = calendar year.
As a result, astronomers on Earth observing a particular Martian surface feature one night, will see that same feature positioned around 10° further west on Mars (or closer to its morning limb) the next night at the same civil time.
UTC, which is used as the basis for official time-of-day radio broadcasts for civil time, is maintained using extremely precise atomic clocks....
) while the year maintains a more uniform duration.
(b) A measure of time that conforms, within a close approximation, to the mean diurnal motion of the Sun and serves as the basis of all civil timekeeping. UT is formally defined by a mathematical formula as a function of sidereal time.
Duffett-Smith, P. "Converting the Local Time to UT," "Converting UT to Local Civil Time," "`Sidereal Time," "Conversion of UT to GST," and "Conversion of GST to UT." §9-13 in Cambridge, England: Cambridge University Press, pp. 12-19, 1992.
5 (from the Julian-date system, which is half a day different from civil time or UT). The standard epoch J2000.0, now used for new star-position catalogues and in solar-system-orbital calculations, means 2000 Jan. 1.
The international prime meridian is no longer precisely the Greenwich meridian, but remains close to it.
Time zone
Although civil time, e.g., the Greenwich Time Signal in the United Kingdom, is now based on UTC, it is still popularly called GMT.
Time based upon the Earth's rotation and the basis for civil time keeping. It is essentially the same as Greenwich Mean Time.
UNIVERSE ...
the local time of day on a line of longitude centered on Greenwich, England (also known as Greenwich Mean Time); it forms the basis for all civil timekeeping
V
variable star ...
 See also: Time, Earth, Astronomy, Meridian, Solar
  
|
RSS
