Before displaying an image of the Moon, Lunar Calculator must first calculate the various orbital parameters and position angles of the Sun and Moon. The elements that you would most frequently refer to are displayed directly in the main interface. All of the background parameters as well as final output ones are displayed in a window.
All the algorithms come from Jean Meeus' "Astronomical Algorithms". Limited explanations of the orbital parameters can be found in "Astronomical Algorithms" or the "Explanatory Supplement of the Nautical Almanac"
yyyy/mm/dd/hh:mn:s Loc |
This is the time header, indicating Local or UTC |
2003/11/15/11:39:35 |
The time |
J.D.: 2452959.23582176 JDE: 2452959.23659722 T= 0.038720 |
Time in Julian days, Ephmeris time, and centuries from 2000 |
Delta T: 67.00 Second |
This is the difference between Terrestrial (Ephemeris) Time and UTC; required because Earth's rotation is not constant |
Age of Moon: 21d 4h 49m |
Days/hours since the most recent new Moon |
Time before next New Moon: 8d 5h 19m |
Days/hours until the next new Moon (useful for "old" crescents) |
Topocentric Data: |
There are two sections, topocentric and geocentric |
RA (2000) 08h 37m 12s |
Right Ascension |
Dec (2000) 23° 04' 54" |
Declination |
Az/Alt Az 273.9° Alt +26.3° |
Azimuth and Altitude of the Moon |
Size 0° 30' 19" |
Observed diameter of the Moon in degrees/minutes/seconds of arc, from your location |
e-m dist km 394134 e-m dist mi 244904 |
Earth-Moon distance (center to observer's location) |
Libration Optical + Physical: |
|
PA of Lunar Axis 15 |
Position Angle on the sky (from north) |
PA of bright limb Chi 103 |
Position Angle of the Moon's bright limb: from Meeus: "Chi is the angle of the midpoint of the illuminated limb of the Moon, reckoned eastward from the North Point of the disk, (not from the axis of rotation of the lunar globe). " |
Solar Longitude -79.8 |
This is the selenographic (lunar) longitude of the subsolar point; remember east is to the right on the moon (from the northern hemisphere) |
Colongitude 169.8 |
|
Solar lat on Moon -0.1 |
This is the selenographic (lunar) latitude of the subsolar point |
e-s dist AU 0.9891119118 |
Earth-Sun distance in Astronomical Units |
e-s dist km 147969035 e-s dist mi 91943696 |
Earth-Sun distance (center to center) |
Geocentric Data: etc. |
Several parameters are repeated for a fictious observer at the center of the Earth; if you are comparing values to those from almanacs, these are the ones to use, NOT the topocentric ones above. |
Orbital Parameters: |
Detailed explanations for these are found elsewhere, since they are not needed for the visual observer. |
appgeolongmoon: 126.121274 |
Apparent geocentric longitude of the Moon |
appgeolatmoon: 5.134280 |
Apparent geocentric latitude of the Moon |
nut in long: -0.00 |
Nutation in longitude |
arglatmoon, F: 82.703362 |
Argument of the Moon's latitude |
meanlonascnodemoon: 50.155409 |
Mean longitude of the ascending node of the Moon |
meanlongperimoon: 240.904168 |
Mean longitude of the perigee of the Moon |
obliquity nutation: 0.00 |
Amount that the obliquity is modified by nutation |
geomeanlongsun: 234.405019154307 |
Geometric mean longitude of the Sun |
meananomsun: 311.401088801213 |
Mean anomaly of the Sun |
suntruelong: 232.94902589771 |
Sun's true longitude |
applongsun: 232.939666128117 |
Apparent longitude of the Sun |
applatsun: 0 |
Apparent latitude of the Sun |
sollong2000: 232.907115897629 |
Solar longitude at epoch 2000.0 |