Mean place is the position of an object on the celestial sphere, as seen from the Sun, referred to the mean equator and equinox at the beginning of the year. It is thus the apparent place corrected for annual parallax, proper motion, precession, aberration, and nutation. All observations of the apparent place of a star made during a particular year may be reduced to the mean place for the beginning of that year, so that they can be intercompared; in practice, though, all observations made over a period of several years are reduced to a common epoch, e.g. J2000.0.