| 释义 |
Annual variation
| (Astron.) | the yearly change in the right ascension or declination of a star, produced by the combined effects of the precession of the equinoxes and the proper motion of the star. |
See also: Variation annual variation
annual variation[′an·yə·wəl ver·ē′ā·shən] (astronomy) The change in the right ascension and declination of a star during one year, due to the combined effect of the star's proper motion and the precession of the equinoxes. (geophysics) A component in the change with time in the earth's magnetic field at a specified location that has a period of 1 year. annual variationThe quantum of yearly change in variation at a place. This is normally indicated on the bottom of a map or chart and must be added/subtracted to/from the figure given on the map after taking into consideration the number of years elapsed since the last survey for the map. Variation is the angular difference between the direction of true north and magnetic north at any given point. |