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Solar longitude, commonly abbreviated as Ls, is the ecliptic longitude of the Sun, i.e. the position of the Sun on the celestial sphere along the ecliptic.It is also an effective measure of the position of the Earth (or any other Sun-orbiting body) in its orbit around the Sun, [1] usually taken as zero at the moment of the vernal equinox. [2]
The mean longitude of the Sun, corrected for the aberration of light, is: L = 280.460 ∘ + 0.9856474 ∘ n {\displaystyle L=280.460^{\circ }+0.9856474^{\circ }n} The mean anomaly of the Sun (actually, of the Earth in its orbit around the Sun, but it is convenient to pretend the Sun orbits the Earth), is:
On a prograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the Sun and a certain distant star are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 = one sidereal day). But it is not until a little later, at time 3, that the Sun is overhead again (1→3 = one solar day). More simply, 1→2 is a complete ...
Ptolemy discusses the correction needed to convert the meridian crossing of the Sun to mean solar time and takes into consideration the nonuniform motion of the Sun along the ecliptic and the meridian correction for the Sun's ecliptic longitude. He states the maximum correction is 8 + 1 ⁄ 3 time-degrees or 5 ⁄ 9 of an hour (Book III ...
Newcomb gives the Right ascension of the fictitious mean Sun, affected by aberration (which is used in finding mean solar time) as [10] τ = 18 h 38 m 45.836 s + 8 640 184.542 s T + 0.0929 s T 2. Authors citing this expression include McCarthy & Seidelmann (p. 13) and the Nautical Almanac Offices of the United Kingdom and United States (p. 73).
It rotates with a sidereal period of exactly 25.38 days, which corresponds to a mean synodic period of 27.2753 days. [9]: 221 [1] [2] [5] Whenever the Carrington prime meridian (the line of 0° Carrington longitude) passes the Sun's central meridian as seen from Earth, a new Carrington rotation begins.
The sun is growing more active than scientists predicted. About every 11 years, the sun's magnetic fields flip, increasing solar activity. That activity can disrupt radio communications and GPS ...
In the introduction to Tables of the Sun, the basis of the tables (p. 9) includes a formula for the Sun's mean longitude at a time, indicated by interval T (in units of Julian centuries of 36525 mean solar days [19]), reckoned from Greenwich Mean Noon on 0 January 1900: Ls = 279° 41' 48".04 + 129,602,768".13T +1".089T 2. . . . . (1)