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  2. Equinox (celestial coordinates) - Wikipedia

    en.wikipedia.org/wiki/Equinox_(celestial...

    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.

  3. Epoch (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Epoch_(astronomy)

    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 ...

  4. Astrological age - Wikipedia

    en.wikipedia.org/wiki/Astrological_age

    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 ...

  5. Ecliptic coordinate system - Wikipedia

    en.wikipedia.org/wiki/Ecliptic_coordinate_system

    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

  6. Earth-centered inertial - Wikipedia

    en.wikipedia.org/wiki/Earth-centered_inertial

    Thus, the vernal equinox, the equatorial plane of the Earth, and the ecliptic plane vary according to date and are specified for a particular epoch. Models representing the ever-changing orientation of the Earth in space are available from the International Earth Rotation and Reference Systems Service .

  7. What did the groundhog see? Punxsutawney Phil’s winter ...

    www.aol.com/news/did-groundhog-see-punxsutawney...

    In reality, winter will end on the spring equinox, known also as the vernal equinox, on March 20 at 5:01 a.m. ET, regardless of Sunday’s prediction. But weather conditions don’t always follow ...

  8. Equatorial coordinate system - Wikipedia

    en.wikipedia.org/wiki/Equatorial_coordinate_system

    Mean equinox of a standard epoch (usually J2000.0, 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

  9. Axial precession - Wikipedia

    en.wikipedia.org/wiki/Axial_precession

    Thus the equinox moved 54° in one direction and then back 54° in the other direction. This cycle took 7200 years to complete at a rate of 54″/year. 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 ...