Diurnal motion of the earth
(gcide) | Diurnal \Di*ur"nal\, a. [L. diurnalis, fr. dies day. See
Deity, and cf. Journal.]
1. Relating to the daytime; belonging to the period of
daylight, distinguished from the night; -- opposed to
nocturnal; as, diurnal heat; diurnal hours.
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2. Daily; recurring every day; performed in a day; going
through its changes in a day; constituting the measure of
a day; as, a diurnal fever; a diurnal task; diurnal
aberration, or diurnal parallax; the diurnal revolution of
the earth.
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Ere twice the horses of the sun shall bring
Their fiery torcher his diurnal ring. --Shak.
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3. (Bot.) Opening during the day, and closing at night; --
said of flowers or leaves.
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4. (Zool.) Active by day; -- applied especially to the eagles
and hawks among raptorial birds, and to butterflies
(Diurna) among insects.
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Diurnal aberration (Anat.), the aberration of light arising
from the effect of the earth's rotation upon the apparent
direction of motion of light.
Diurnal arc, the arc described by the sun during the
daytime or while above the horizon; hence, the arc
described by the moon or a star from rising to setting.
Diurnal circle, the apparent circle described by a
celestial body in consequence of the earth's rotation.
Diurnal motion of the earth, the motion of the earth upon
its axis which is described in twenty-four hours.
Diurnal motion of a heavenly body, that apparent motion of
the heavenly body which is due to the earth's diurnal
motion.
Diurnal parallax. See under Parallax.
Diurnal revolution of a planet, the motion of the planet
upon its own axis which constitutes one complete
revolution.
Syn: See Daily.
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