astronomical horizon


Atmospheric Sciences (English-Chinese) dictionary. 2014.

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  • horizon — /həˈraɪzən / (say huh ruyzuhn) noun 1. the line or circle which forms the apparent boundary between earth and sky (apparent horizon or visible horizon). 2. Astronomy a. the plane which is tangent to the earth at the place of the observer and… …   Australian English dictionary

  • Astronomical chronology — Astronomical chronology, or astronomical dating, is a technical method of dating events or artifacts that are associated with astronomical phenomena. Written records of historical events that include descriptions of astronomical phenomena have… …   Wikipedia

  • Astronomical coordinate systems — are coordinate systems used in astronomy to describe the location of objects in the sky and in the universe. The most commonly occurring such systems are coordinate systems on the celestial sphere, but extragalactic coordinates systems are also… …   Wikipedia

  • astronomical map — Introduction       any cartographic representation of the stars, galaxies, or surfaces of the planets and the Moon. Modern maps of this kind are based on a coordinate system analagous to geographic latitude and longitude. In most cases, modern… …   Universalium

  • Astronomical clock — An astronomical clock is a clock with special mechanisms and dials to display astronomical information, such as the relative positions of the sun, moon, zodiacal constellations, and sometimes major planets. DefinitionThe term is loosely used to… …   Wikipedia

  • Astronomical naming conventions — In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are… …   Wikipedia

  • Astronomical Netherlands Satellite — Infobox Space telescope name = Astronomical Netherlands Satellite (ANS) caption = The flight spare for the satellite organization = NISR / NASA major contractors = alt names = Astronomische Nederlandse Satelliet nssdc id = location = orbit type …   Wikipedia

  • astronomical twilight — noun : the period after sunset or before sunrise ending or beginning when the sun is about 18 degrees below the horizon * * * either of two periods of partial darkness, after sunset or before sunrise, when the center of the sun is more than 6°… …   Useful english dictionary

  • astronomical twilight — either of two periods of partial darkness, after sunset or before sunrise, when the center of the sun is more than 6° but less than 18° below the horizon. * * * …   Universalium

  • astronomical twilight — noun The period in which the sun is between 12° 18° below the horizon in the morning and evening …   Wiktionary

  • astronomical twilight — The period before sunrise and after sunset when sun’s center is between 12° and 18° below sea level horizon. This may be regarded for all practical purposes as synonymous with complete darkness …   Aviation dictionary

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