phase of the moon

Thesaurus

Noun

phase of the moon - a time when the Moon presents a particular recurring appearancephase - (astronomy) the particular appearance of a body's state of illumination (especially one of the recurring shapes of the part of Earth's moon that is illuminated by the sun); "the full phase of the moon"period, period of time, time period - an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period"new moon, new phase of the moon - the time at which the Moon appears as a narrow waxing crescenthalf-moon - the time at which the Moon is at first or last quarter when half its face is illuminatedfull, full moon, full phase of the moon, full-of-the-moon - the time when the Moon is fully illuminated; "the moon is at the full"

phase of the moon

Used humorously as a random parameter on which something issaid to depend. Sometimes implies unreliability of whateveris dependent, or that reliability seems to be dependent onconditions nobody has been able to determine. "This featuredepends on having the channel open in mumble mode, having thefoo switch set, and on the phase of the moon."

See also heisenbug.

True story: Once upon a time there was a bug that really diddepend on the phase of the moon. There was a littlesubroutine that had traditionally been used in variousprograms at MIT to calculate an approximation to the moon'strue phase. GLS incorporated this routine into a Lispprogram that, when it wrote out a file, would print atimestamp line almost 80 characters long. Very occasionallythe first line of the message would be too long and wouldoverflow onto the next line, and when the file was later readback in the program would barf. The length of the firstline depended on both the precise date and time and the lengthof the phase specification when the timestamp was printed, andso the bug literally depended on the phase of the moon!

The first paper edition of the Jargon File (Steele-1983)included an example of one of the timestamp lines thatexhibited this bug, but the typesetter "corrected" it. Thishas since been described as the phase-of-the-moon-bug bug.

Phase of the Moon

one of the different shapes of the visible part of the moon. The changes of phase of the moon are caused by variations in the conditions under which the sun illuminates the dark lunar sphere as the moon moves in its orbit about the earth. As the relative positions of the earth, the moon, and the sun change, the terminator—that is, the boundary between the illuminated and unilluminated parts of the lunar disk—moves, thus causing the observed changes in the configuration of the visible part of the moon (see Figure 1).

Figure 1. Changes of phase of the moon

phase of the moon

phase of the moon

phase of the moon

Phase of the Moon

phase of the moon

Words related to phase of the moon

noun a time when the Moon presents a particular recurring appearance

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