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Webster 1913 Edition


Sidereal

Si-de′re-al

,
Adj.
[L.
sidereus
, from
sidus
,
sideris
, a constellation, a star. Cf.
Sideral
,
Consider
,
Desire
.]
1.
Relating to the stars; starry; astral;
as,
sidereal
astronomy
.
2.
(Astron.)
Measuring by the apparent motion of the stars; designated, marked out, or accompanied, by a return to the same position in respect to the stars;
as, the
sidereal
revolution of a planet; a
sidereal
day.
Sidereal clock
,
day
,
month
,
year
.
See under
Clock
,
Day
, etc.
Sideral time
,
time as reckoned by sideral days, or, taking the sidereal day as the unit, the time elapsed since a transit of the vernal equinox, reckoned in parts of a sidereal day. This is, strictly, apparent sidereal time, mean sidereal time being reckoned from the transit, not of the true, but of the mean, equinoctial point.

Webster 1828 Edition


Sidereal

SID'ERAL

, SIDE'REAL,
Adj.
[L. sideralis, from sidus, a star.]
1.
Pertaining to a star or stars; astral; as sideral light.
2.
Containing stars; starry; as sidereal regions. Sidereal year, in astronomy, the period in which the fixed stars apparently complete a revolution and come to the same point in the heavens.

Definition 2024


sidereal

sidereal

English

Alternative forms

Adjective

sidereal (not comparable)

  1. Of or relating to the stars.
    • 1919, Hector Macpherson, S.Chapman (series editor), Men of Science: Herschel, Chapter V,
      The field of sidereal astronomy, therefore, was virtually untrodden when, shortly after the beginning of his telescopic work, Herschel began his first review of the heavens.
  2. (astronomy) Relating to a measurement of time relative to the position of the stars.
    • 1903, Percival Lowell, The Solar System, Chapter I,
      Then, from a sufficient number of observations of synodic periods to give their mean, we obtain the sidereal period, or period with reference to the stars.
  3. (astronomy) Relating to a measurement of time relative to the point of the vernal equinox.

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