astronomical day


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Related to astronomical day: Astronomical Unit, astronomical year, Astronomical time

astronomical day

[‚as·trə′näm·ə·kəl ′dā]
(astronomy)
A mean solar day beginning at mean noon, 12 hours later than the beginning of the civil day of the same date; astronomers now generally use the civil day.
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References in periodicals archive ?
239]Pu [alpha]-decay over astronomical day (since 6 to 18 h by local, longitude, time) and, second, measured over astronomical night (since 18 to 6 h, in continuation of the first series) and inverted.
The cold weather came despite the spring equinox, seen by some as the first day of spring, when the astronomical day and night are equal.

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