Phase display (displayed in the calendar and clock in) doing NoteIcon perpetual calendar and moon, I looked up some open source code and data and found that in a number of open source projects in these three confused, it is necessary to re-stroked it.
First, the phase of the moon (moon phase)
In the "university astronomy" [1] on page 56 it says:
Although any moment the moon is always illuminated by the sun half sphere, but the size and shape that we can see the bright part of the moon is different, there is wane change "profit and loss", and this phenomenon is called "phase of the moon." Moon phase variation is periodic (FIG. 5-3). Reasons for the formation of the phases of the moon, the moon first, they do not luminous nor light, but only reflect sunlight; and second, day, month, the relative position of the three is changing, and there are periodic. This phase change month period called "lunar month", a lunar month average of 29.5306 mean solar day, up to 29.82917d, a minimum of 29.2944d. "New Moon" or "New Moon" Sun and Moon consistency, occurred in the lunar first day, but not monthly; "look" or "Full Moon" Sun and Moon clash took place in the Lunar 15, 16, the full moon. When the Moon is at 90 ° west of the Sun "bottom chord", when the moon is 90 ° east of the Sun "winding", respectively, occurred in the lunar Nianer or Niansan and seventh, eight, you will see only the moon is illuminated half hemisphere. With the sun and the moon yellow graded by the poor level of moon phase moon and new moon are also graded.
I did not understand? Simple and crude to say: As the Earth blocking sunlight, causing us to see "Moon rarely round," the moon wanes change is the phase of the moon.
Moon phase most common problem is easy and "months" confused, that is expected to be calculated by months moon phase: know a lunar month (lunar month) the exact start time (some can not even calculate the exact source code start time, only monthly average length, i.e. above said 29.5306), then takes an intermediate value is the half moon (full moon), is taken 1/4 "winding", is taken 3/4 "lower chord" - if this method use of words, such a statement would not have "Full moon sixteen round" the. This is a long calculation using the average monthly phases of the moon's source code, Baidu, you can know has been widely reproduced in the country:
https://www.codeproject.com/Articles/100174/Calculate-and-Draw-Moon-Phase
When astronomical calculations, due to the phase of the moon is, the month, day three of the angle formed, but also consider various factors orbit, so a lot of trouble, specific calculation methods can be found in "fun algorithms" [2] section 11.3.1 instructions and source code book provided. Additional information:
1, the moon and the New Moon in the source code book gives a little small bug, easy to fix, I'll give some face not explained in detail.
2, the sun and the moon is calculated moon given source code book is computationally, month, day three when the angle is zero source, after the read but is easily possible to calculate the moon change (an angle of 180 degrees ), first quarter (90), in its last quarter (270 degrees) and the like. NoteIcon calculates the full moon (Mochizuki) in time with it.
3, the sun and the moon moon arithmetic book from the English version of "astronomical algorithm" [3], the Internet can scan down to the original book version and errata. Also the author of "birthday astronomical calendar" Mr. Xu Jianwei translation software Chinese version of the book, although not officially published, but the Internet can also be down to the electronic version. But Chinese version does not fully translated, so to see if the proposal is still shining and the English to see. In addition, "birthday astronomical calendar" is open source, but with js written, I see dizziness, [2] there is no C ++ code is more familiar.
Second, months (moon age)
If the crescent moon and then to from the moon, the moon full moon process as "life", that is born (new moon), Youth (waxing), middle (full moon), the elderly (waning moon), death (Crescent ), then a crescent from the time between the next new moon, that is to say above [1] in the time between the "lunar month" is the age of the moon, the "months."
I did not understand? Simple and crude explanations: first, the second and so on Lunar New Year's date digital equivalent of the moon "age", that is, the moon in the first day of birth, has grown to fifteen full moon, then gradually aging, until the end of February nineteen (Satsuki ) or thirty (Otsuki) on bye your leave.
In the case of New Moon Sun and Moon can be accurately calculated point in time, namely the lunar calendar to calculate the date of age will not have any problems down the row from the first day on the line. But you can not turn calculation, that is calculated from the phase of the moon of age. Full moon, for example, in terms of age should be fifteen, but it may actually sixteen or even seven. However, when used as [2] Iterative methods moon phase time accurately, the initial value of the iteration as months, in respect noteicon 1/2 month-long time as an initial value of the iteration find Mochizuki, then iterative approximation.
Third, the ratio of surface to illuminate the month (Illuminated Fraction of the Moon's Disk)
Many watches have called "moon phase" display, in fact, I think we should say shows the "Moon illuminates the proportion of surface", that is, how much of the entire lunar surface is illuminated, so that we can see.
It is indeed easier to part and "moon phase" confused, but the phases of the moon is calculated PERSPECTIVE VIEW illuminated and calculating the ratio of lunar surface is not the same, so that in [3], "moon phase (Phases of the Moon)" and "May illuminate proportion surface (Illuminated Fraction of the Moon's Disk)" is in a separate two chapters say, the formula is not the same. Book simplified formulas readily translated into code can calculate the ratio of lunar surface illuminated by the mechanical time mechanics is given, this value drawn by the moon, the naked eye is on the ground in an accurate reflection of the moon . Central NoteIcon clock and calendar of the moon is so lower right corner of the painting.
If I like the above given link the code with the same month old painting moon, met "the moon sixteen-five round" when dumbfounded.
Reference material
. [1] Sun Jinlong, Lide Fan edited by University astronomy [M] Kaifeng: Henan University Press, 2005.03.
[2] Wang Xiaohua the fun algorithm [M] Beijing: People's Posts and Telecommunications Press, 2015.04.
[3] . .Jean Meeus Astronomical algorithms - 2nd ed Willmann-Bell, Inc. 1998.