Time Interval Constants

The following time interval constants are defined:

 

1. Units of Time

Identifier Value Meaning
Day 1.0 day
Hour 1/24 hour
Minute 1/1440 minute
Second 1/86400 second 
Century 36525.0 century (100 Julian years)

   

2. Length of the Year

Identifier Value Meaning
JulianYear 365.25 length of Julian year (365d 06:00:00)
GregorianYear 365.2425 length of Gregorian year (365d 05:49:12)
TropicalYear 365.2421897 length of tropical year (equinox to equinox) (365d 05:48:45.19)
SiderealYear 365.25636 length of sidereal year (fixed star to fixed star) (365d 06:09:10) 
AnomalisticYear 365.25964 length of anomalistic year (perihelion to perihelion) (365d 06:13:53)

   

3. Length of the Month

Identifier Value Meaning
SynodicMonth 29.53059 length of synodic month (new moon to new moon) (29d 12:44:03)
TropicalMonth 27.32158 length of tropical month (equinox to equinox) (27d 07:43:05)
SiderealMonth 27.32166 length of sidereal month (fixed star to fixed star) (27d 07:43:12)
AnomalisticMonth 27.55455 length of anomalistic month (perigee to perigee) (27d 13:18:33)
DraconicMonth 27.21222 length of draconic month (node to node) (27d 05:05:36)

 

4. Planetary Periods

Identifier Value Meaning
MerTropical 0.24084445 * 365.25 Mercury's tropical period (0.24084445 Julian years)
VenTropical 0.61518257 * 365.25 Venus' tropical period (0.61518257 Julian years)
MarTropical 1.88071105 * 365.25 Mars' tropical period (1.88071105 Julian years)
JupTropical 11.85652502 * 365.25 Jupiter's tropical period (11.85652502 Julian years)
SatTropical 29.42351935 * 365.25 Saturn's tropical period (29.42351935 Julian years)
UraTropical 83.74740682 * 365.25 Uranus' tropical period (83.74740682 Julian years)
NepTropical 163.7232045 * 365.25 Neptune's tropical period (163.7232045 Julian years)
MerSidereal 87.96858 Mercury's sidereal period (87.96858 days)
VenSidereal 224.70065 Venus' sidereal period (224.70065 days)
MarSidereal 686.98038 Mars' sidereal period (686.98038 days)
JupSidereal 4332.58686 Jupiter's sidereal period (4332.58686 days)
SatSidereal 10759.20217 Saturn's sidereal period (10759.20217 days)
UraSidereal 30685.20533 Uranus' sidereal period (30685.20533 days)
NepSidereal 60189.52058 Neptune's sidereal period (60189.52058 days)
MerSynodic 115.8775 Mercury's synodic period (115.8775 days)
VenSynodic 583.9214 Venus' synodic period (583.9214 days)
MarSynodic 779.9361 Mars'  synodic period (779.9361 days)
JupSynodic 398.8840 Jupiter's synodic period (398.8840 days)
SatSynodic 378.0919 Saturn's synodic period (378.0919 days)
UraSynodic 369.6560 Uranus' synodic period (369.6560 days)
NepSynodic 366.7207 Neptune's synodic period (366.7207 days)

 

5. Other Periods

Identifier Value Meaning
Saros 6585.3333 length of Saros cycle 
Inex 10572.0 length of Inex cycle 
MetonicCycle 6940.6 length of Metonic cycle 

Alcyone Ephemeris Documentation
(C) 2007 Alcyone Software