Lunar Quarter Phases Dates Calculator
Ephemeris Span: BC 9999-Apr to AD 9999-Nov
Built Around the NASA/JPL Horizons API
Program by Jay Tanner - 2025
Date
Time Zone
Daylight/Summer Time
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MOON PHASE ANGLES AND QUARTER PHASE DATES Ephemeris Span: BC 9999-Apr to AD 9999-Nov Local Calendar Date : AD 2025-Nov (Gregorian Calendar) Local Time Zone Offset : -05:00 (-West) Daylight/Summer Time : No ---------------------------------------------- TABLE OF CALENDAR DATES OF MOON QUARTER PHASES AD 2025-Nov-05 Full Moon AD 2025-Nov-12 Last Quarter AD 2025-Nov-20 New Moon AD 2025-Nov-28 First Quarter ----------------------------------------------------------- TABLE OF SIMPLE MOON PHASE ANGLES FOR 00:00 ON EACH DATE =========================================================== Loc_Date Loc_Time Cnst Julian_Date_UT Phase_Ang ============== ======== ==== ================= ========= AD 2025-Oct-31 00:00:00 Cap 2460979.708333333 108.21940 AD 2025-Nov-01 00:00:00 Aqr 2460980.708333333 120.68475 AD 2025-Nov-02 00:00:00 Psc 2460981.708333333 133.62474 AD 2025-Nov-03 00:00:00 Psc 2460982.708333333 147.04120 AD 2025-Nov-04 00:00:00 Psc 2460983.708333333 160.88392 AD 2025-Nov-05 00:00:00 Ari 2460984.708333333 175.04410 AD 2025-Nov-06 00:00:00 Ari 2460985.708333333 189.36131 AD 2025-Nov-07 00:00:00 Tau 2460986.708333333 203.64657 AD 2025-Nov-08 00:00:00 Tau 2460987.708333333 217.71610 AD 2025-Nov-09 00:00:00 Gem 2460988.708333333 231.42351 AD 2025-Nov-10 00:00:00 Gem 2460989.708333333 244.67918 AD 2025-Nov-11 00:00:00 Cnc 2460990.708333333 257.45288 AD 2025-Nov-12 00:00:00 Leo 2460991.708333333 269.76369 AD 2025-Nov-13 00:00:00 Leo 2460992.708333333 281.66416 AD 2025-Nov-14 00:00:00 Leo 2460993.708333333 293.22461 AD 2025-Nov-15 00:00:00 Vir 2460994.708333333 304.52044 AD 2025-Nov-16 00:00:00 Vir 2460995.708333333 315.62342 AD 2025-Nov-17 00:00:00 Vir 2460996.708333333 326.59629 AD 2025-Nov-18 00:00:00 Vir 2460997.708333333 337.49039 AD 2025-Nov-19 00:00:00 Lib 2460998.708333333 348.34552 AD 2025-Nov-20 00:00:00 Lib 2460999.708333333 359.19173 AD 2025-Nov-21 00:00:00 Sco 2461000.708333333 10.05260 AD 2025-Nov-22 00:00:00 Oph 2461001.708333333 20.94951 AD 2025-Nov-23 00:00:00 Sgr 2461002.708333333 31.90622 AD 2025-Nov-24 00:00:00 Sgr 2461003.708333333 42.95304 AD 2025-Nov-25 00:00:00 Sgr 2461004.708333333 54.13002 AD 2025-Nov-26 00:00:00 Cap 2461005.708333333 65.48831 AD 2025-Nov-27 00:00:00 Cap 2461006.708333333 77.08936 AD 2025-Nov-28 00:00:00 Aqr 2461007.708333333 89.00126 AD 2025-Nov-29 00:00:00 Aqr 2461008.708333333 101.29151 AD 2025-Nov-30 00:00:00 Psc 2461009.708333333 114.01595 AD 2025-Dec-01 00:00:00 Psc 2461010.708333333 127.20371 ============== ======== ==== ================= ========= Loc_Date Loc_Time Cnst Julian_Date_UT Phase_Ang ===========================================================
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SEEKING THE CALENDAR DATES OF THE LUNAR PHASES Given any month within the range of the ephemeris, this program will first generate the table of lunar phase angles for 00:00 local time on each date of the given month, then it will scan the table and extract ONLY the dates of the lunar phases. The clock time of the event is NOT computed. IMPORTANT NOTE: Make sure to use the correct Time Zone and Daylight/Summer time setting or the calendar date could be 1 day in error. Visually seeking the phase dates within the table is actually quite simple as long as we only want the calendar dates without the actual event times. We scan forward through the zero-indexed table starting at array index [1] and test the simple phase angle values in pairs to find the phase dates. Any phase occuring near the beginning of the month may possibly be repeated again near the end of the month, such as a second (blue) full moon if there is a full moon near the beginning of the month. If there are multiple similar phases, such as a blue moon or any other phase that repeats during the month, it will also be listed. --------------------------------------------------------- The table lines array is indexed from [0] and the pairing works according to this algorithm working forward from [1] up until reaching [wCount]: PrevLine = wArray[CurrIndex - 1] CurrLine = wArray[CurrIndex] ------------------------------------------------------------ The phase angle in degrees is at the end of each table line. PrevPA = Trimmed last 10 characters of raw (PrevLine). CurrPA = Trimmed last 10 characters of raw (CurrLine). When two successive values meet the test conditions, then the first of the two corresponding dates is the phase date on the calendar. ------------------------------------------------------------- Phase_Ang Phase_ID Phase Seeking Rule Within Table --------- ------------- -------------------------------- 0 New Noon (CurrPA - PrevPA) < 0 90 First Quarter (PrevPA < 90 and CurrPA >= 90) 180 Full Moon (PrevPA < 180 and CurrPA >= 180) 270 Last Quarter (PrevPA < 270 and CurrPA >= 270) ------------------------------------------------------------- Following these rules yields the moon quarter phases date table for the current given month as computed above.
PHP Program by Jay Tanner
v1.00 - Revised: 1970-January-01-Thursday at Local Time 12:00:00 AM (UTC−05:00)