Information AboutJ2000 |
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The J2000.0 Epoch is used in Astronomy . It is precisely . Since the Right Ascension and Declination of stars are constantly changing due to Precession , (and, for relatively nearby stars due to Proper Motion ), astronomers always specify these with reference to a particular epoch. The earlier epoch that was in standard use was the B1950.0 epoch. When the ''mean'' is averaged out or omitted. Novices are sometimes confused by finding that the Earth's rotational North pole does not point quite at the J2000 celestial pole at the epoch J2000.0; the reason is that the true pole of epoch suffers Nutation ("is nutated") away from the mean one. The same differences pertain to the equinox. The "J" in the prefix indicates that it is a Julian Epoch , as opposed to a Besselian Epoch . SEE ALSO EXTERNAL LINKS
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