Advertisement

sidereal (adj.)

also siderial, 1630s, "star-like;" 1640s, "of or pertaining to the stars," earlier sideral (1590s), from French sidereal (16c.), from Latin sidereus "starry, astral, of the constellations," from sidus (genitive sideris) "star, group of stars, constellation," which is of uncertain origin, perhaps from PIE root *sweid- "to shine" (source also of Lithuanian svidus "shining, bright").

Sidereal time is measured by the apparent diurnal motion of the fixed stars. The sidereal day begins and ends with the passage of the vernal equinox over the meridian and is about four minutes shorter than the solar day, measured by the passage of the sun over the meridian.

Others are reading

Advertisement
Advertisement
Definitions of sidereal from WordNet

sidereal (adj.)
of or relating to the stars or constellations;
sidereal bodies
the sidereal system
sidereal (adj.)
(of divisions of time) determined by daily motion of the stars;
sidereal time
From wordnet.princeton.edu