sidereal day
noun
Definition of sidereal day
: the interval between two successive transits of a point on the celestial sphere (such as the vernal equinox) over the upper meridian of a place : 23 hours, 56 minutes, 4.1 seconds of mean time
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1764
First Known Use of sidereal day
1764
Learn More about sidereal day
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Britannica.com: Encyclopedia article about sidereal day
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