saɪˈdɪərɪəl adj. of or
concerning the constellations or fixed stars. øsidereal clock a clock
showing sidereal
time. sidereal
day the time
between successive meridional transits of a
star or
esp. of the
first point of
Aries,
about four minutes shorter
than the
solar day. sidereal time time
measured by the
apparent diurnal motion of the stars. sidereal
year a year longer than the solar year by 20 minutes 23 seconds
because of
precession. [L sidereus f. sidus sideris star]