9 articles for "True"
True Anomaly [Astro*Index]Angular distance from perihelion to a given orbital position of a body, measured from the Sun.
See also:True Anomaly [Munkasey M.]
♦ Ellipse ♦ Angular Distance ♦ Perihelion
The true arc of orbit from a Body's Perihelion Clock-wise or Eastward to the Body's present position. See also: "Anomaly".
See also:True Equinox [Munkasey M.]
♦ Anomaly ♦ Ellipse ♦ Angular Distance ♦ Perihelion
The point in space defined where the intersection ofthe true Celestial Equator of date crosses the Ecliptic.
See also:True Horizon [Astro*Index]
♦ Ellipse ♦ Angular Distance ♦ Perihelion
Synonym for Rational Horizon.
See also:True Local Time [Astro*Index]
♦ Horizontal Coordinates ♦ Rational Horizon
(TLT)
Obsolete term. It led to much confusion, as it suggests that other time measurements are untrue (or less accurate). Sundial Time.
See also:True Lunar Node [Astro*Index]
♦ Local Apparent Time ♦ Time
The line formed by the intersection of the Moon's Instantaneous Orbital Plane (specified by the Moon's position and velocity vectors) and the Ecliptic, projected onto the Celestial Sphere. Also, the points of intersection of the Moon's Instantaneous Orbital Ellipse with the Ecliptic. The longitude of a true lunar node can differ from the mean node by up to 1.75°, and can be retrograde or direct. The mean node is always retrograde and moves at a constant rate.
See also:True Solar Day [DeVore]
♦ Lunar Node ♦ Mean Lunar Node ♦ Direct Motion ♦ Retrograde Motion ♦ Orbital Period ♦ Ecliptic ♦ Celestial Sphere
v. Day.
See also:True Sun [Astro*Index]
♦ Day ♦ Time
An unfortunate term, as it carries the suggestion that other measurements are false (or, perhaps, inaccurate). Modern usage prefers the term Geometric Position, which is obtained by "freeing" the Apparent Sun's position from the effects of Aberration (Light-Time). Essentially, the Geometric Position is that which would be observed if light travelled instantaneously from the Sun to the Earth. Thus, the Geometric Position (the True Sun) is advanced over the geocentric longitude of the Apparent Sun.
See also:True Time [Astro*Index]
♦ Light-time Aberration ♦ Geometric Position ♦ Apparent Sun
Unfortunate term, as it suggests that other time measurements are untrue (or less accurate).
See also:
♦ Local Apparent Time
Astro*Index Copyright © 1997 Michael Erlewine
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