MoonPhase
gives moon phase fraction of illumination for the current date.
MoonPhase[datespec]
gives moon phase fraction of illumination for the specified date.
MoonPhase[property]
gives the property of the moon phase for the current date.
MoonPhase[datespec,property]
gives the property of the moon phase for the specified date.
Details and Options
- The phase of the Moon, also known as the lunar phase, describes the illumination of the lunar surface by the Sun as seen from Earth.
- MoonPhase[] makes use of $TimeZone to determine your time zone.
- datespec can be a DateObject expression, a TimeObject expression or a date string.
- datespec is assumed to be in $TimeZone, unless it is a DateObject or TimeObject expression with an explicit TimeZone option value.
- If datespec is a list of dates, then the results will be given as EventSeries or TimeSeries objects.
- datespec can be specified as {start,end,increment} for compatibility with DateRange specifications.
- MoonPhase["Fraction"] is equivalent to MoonPhase[].
- MoonPhase can accept the following values for property:
-
"Fraction" or "IlluminationFraction" fraction of illumination, from 0 to 1 "SignedFraction" or "SignedIlluminationFraction" signed fraction of illumination, from -1 to 1 "PhaseAngle" lunation angle, from 0 to 2π "PhaseAngleFraction" fraction of lunation angle, from 0 to 1 "Name" name of the moon phase "Icon" icon representing the moon phase - MoonPhase[…,Method"method"] specifies how moon phases are defined. Fraction of illumination, as observed from the center of the Earth, is used by default.
- Possible settings for the Method option include:
-
"Illumination" phase defined by fraction of illumination of the Moon "EclipticLongitude" phase defined by Moon‐Sun ecliptic longitude difference
Examples
open all close allBasic Examples (4)
Scope (7)
Dates can be specified as a DateObject:
Generalizations & Extensions (1)
IconData can accept the signed fraction of the moon phase as its second argument:
Options (1)
Method (1)
By default, MoonPhase uses illumination of the Moon by the Sun to compute properties:
Alternatively, use a method based on the ecliptic longitude difference between Moon and Sun:
Possible Issues (1)
The names of moon phases are based on the illumination fraction value. On a given day, the name of the moon phase may change, depending on what time it is. For example, a full moon does not last a full day, so even if a full moon occurs on that day, you may have to change the time in order to get the phase you might expect:
Text
Wolfram Research (2014), MoonPhase, Wolfram Language function, https://reference.wolfram.com/language/ref/MoonPhase.html (updated 2025).
CMS
Wolfram Language. 2014. "MoonPhase." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2025. https://reference.wolfram.com/language/ref/MoonPhase.html.
APA
Wolfram Language. (2014). MoonPhase. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/MoonPhase.html