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The currently used standard equinox and epoch is J2000.0, which is January 1, 2000 at 12:00 TT. The prefix "J" indicates that it is a Julian epoch. The previous standard equinox and epoch was B1950.0, with the prefix "B" indicating it was a Besselian epoch. Before 1984 Besselian equinoxes and epochs were used.
The difference between reference to an epoch alone, and a reference to a certain equinox with equator or ecliptic, is therefore that the reference to the epoch contributes to specifying the date of the values of astronomical variables themselves; while the reference to an equinox along with equator/ecliptic, of a certain date, addresses the ...
Mean equinox of a standard epoch (usually the J2000.0 epoch, but may include B1950.0, B1900.0, etc.) is a fixed standard direction, allowing positions established at various dates to be compared directly. Mean equinox of date
A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above the equator, rather than north or south of the ...
The equinox coincided with the epoch at the beginning of the Kali Yuga in −3101 and again 3,600 years later in 499. The direction changed from prograde to retrograde midway between these years at −1301 when it reached its maximum deviation of 27°, and would have remained retrograde, the same direction as modern precession, for 3600 years ...
I don't think the distinction made in this article between equinox and epoch (see epoch (astronomy)) accurately reflects modern usage.In astronomy literature, I have never seen the word equinox refer to a time basis; the word epoch is always used as a basis for the coordinate system itself, i.e. precession and nutation changing the celestial equator used for declination and right ascension.
In the astrological age that preceded the time of Hipparchus, the vernal equinox had taken place when the Sun was in the constellation of Taurus, and during that previous epoch the constellations of Canis Minor (The Dog), Hydra (The Snake), Corvus (The Raven), and Scorpius (The Scorpion) – that is, the constellations that correspond to the ...
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]