SINCE 1828

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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

First Known Use of sidereal day

1764

Learn More about sidereal day

Britannica.com: Encyclopedia article about sidereal day

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