declination constant

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• Declination — For other uses, see Declination (disambiguation). In astronomy, declination (abbrev. dec or δ) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is… …   Wikipedia

• Magnetic declination — Example of magnetic declination showing a compass needle with a positive (or easterly ) variation from geographic north. Magnetic declination is the angle between magnetic north (the direction the north end of a compass needle points) and true… …   Wikipedia

• Aberration of light — Light from location 1 will appear to be coming from location 2 for a moving telescope due to the finite speed of light, a phenomenon known as the aberration of light. The aberration of light (also referred to as astronomical aberration or stellar …   Wikipedia

• Sundial — A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style (a thin rod or a sharp, straight edge) onto a flat surface marked with lines indicating… …   Wikipedia

• Contour line — This article is about lines of equal value in maps and diagrams. For more meanings of the word contour , see Contour (disambiguation). The bottom part of the diagram shows some contour lines with a straight line running through the location of… …   Wikipedia

• Equation of time — The equation of time is the difference over the course of a year between time as read from a sundial and time as read from a clock, measured in an ideal situation (ie. in a location at the centre of a time zone, and which does not use daylight… …   Wikipedia

• navigation — navigational, adj. /nav i gay sheuhn/, n. 1. the act or process of navigating. 2. the art or science of plotting, ascertaining, or directing the course of a ship, aircraft, or guided missile. [1520 30; < L navigation (s. of navigatio) a voyage.… …   Universalium

• geomagnetic field — Magnetic field associated with the Earth. It is essentially dipolar (i.e., it has two poles, the northern and southern magnetic poles) on the Earth s surface. Away from the surface, the field becomes distorted. Most geomagnetists explain the… …   Universalium

• Meridian circle — Groombridge transit circle of 1806 The meridian circle, transit circle, or transit telescope is an instrument for observing the time of stars passing the meridian, at the same time measuring its angular distance from the zenith. The idea of… …   Wikipedia

• telescope — /tel euh skohp /, n., adj., v., telescoped, telescoping. n. 1. an optical instrument for making distant objects appear larger and therefore nearer. One of the two principal forms (refracting telescope) consists essentially of an objective lens… …   Universalium

• Equatorial mount — An equatorial mount is a mount that has one rotational axis parallel to the Earth s axis of rotation [cite web | url = http://www.astrogea.org/soldevilla/las monturas.htm | title = LAS MONTURAS | publisher = Observatorio J. A. Soldevilla] [cite… …   Wikipedia