Astronomical day

Also found in: Encyclopedia, Wikipedia.
See under Day.
a period equal to the mean solar day, but beginning at noon instead of at midnight, its twenty-four hours being numbered from 1 to 24; also, the sidereal day, as that most used by astronomers.

See also: Astronomical, Day

References in periodicals archive ?
Note that each Julian day begins at noon (12:00) in Greenwich Mean Time, because in Herschel's era the astronomical day likewise began at noon.
CARDIFF Family astronomical day at the National Museum.
The extra second at midnight on New Year's Eve to align the atomic clocks with the astronomical day? And, talking of alignment, what about the moon Venus and Jupiter on December 1?
As obtained in this experimental research, the sequence of the shapes of histograms (the spectra of the amplitudes of fluctuations), measured during an astronomical day from 6 h to 18 h of the local time, is very similar (with high precision of probability) to the sequence of the histogram shapes obtained during an astronomical night from 18 h to 6 h of the local time a half of year later in exact.
Full browser ?