Astronomy¶
Woxi computes astronomical quantities from the algorithms in Meeus's
Astronomical Algorithms: lunar phases, Sun/Moon positions, sidereal
time, sunrise/sunset, and eclipse predictions. Locations must be given
explicitly as GeoPosition[{lat, lon}] (or a bare {lat, lon} pair):
determining $GeoLocation needs a GeoIP lookup, so — like wolframscript
without internet access — Woxi leaves the location unresolved and a call
that omits one stays unevaluated. All returned dates are UTC instants
(TimeZone 0.), whereas wolframscript localizes them to the location's
time zone.
Positions are topocentric — the observer sits on the Earth's surface, so the Moon's roughly one-degree parallax and the atmosphere's refraction of the altitude are both included. Truncated series cannot reach the accuracy of a full ephemeris, so the expected outputs below are written as regular expressions that pin the digits Woxi and wolframscript agree on: a few arcseconds for a position, a few tens of seconds for a phase or eclipse time, and about half a minute for a sunrise (whose horizon threshold the two engines define slightly differently).
MoonPhase¶
The illuminated fraction of the Moon, or the phase name as an entity:
NewMoon, FullMoon & MoonPhaseDate¶
The first new/full moon (or any principal phase) after a date:
$ wo 'FullMoon[DateObject[{2024, 1, 1}]]'
DateObject\[\{2024, 1, 25, 17, 5[34], \d+\.\d+\}, Instant, Gregorian, 0\.\] (regex)
$ wo 'MoonPhaseDate[DateObject[{2024, 4, 1}], "FirstQuarter"]'
DateObject\[\{2024, 4, 15, 19, 13, \d+\.\d+\}, Instant, Gregorian, 0\.\] (regex)
SunPosition & MoonPosition¶
Azimuth (from north) and altitude, or right ascension — in hours, as
right ascension is customarily written — and declination with
CelestialSystem -> "Equatorial":
$ wo 'SunPosition[GeoPosition[{40.11, -88.24}], DateObject[{2024, 6, 21, 18, 0, 0}]]'
\{Quantity\[184\.0\d+, AngularDegrees\], Quantity\[73\.29\d+, AngularDegrees\]\} (regex)
$ wo 'MoonPosition[GeoPosition[{0, 0}], DateObject[{2024, 1, 1, 0, 0, 0}], CelestialSystem -> "Equatorial"]'
\{Quantity\[10\.6612\d+, HoursOfRightAscension\], Quantity\[12\.728\d+, AngularDegrees\]\} (regex)
SiderealTime¶
Local apparent sidereal time:
$ wo 'SiderealTime[GeoPosition[{0, 0}], DateObject[{1987, 4, 10}]]'
Quantity\[MixedMagnitude\[\{13, 10, 4[56]\.\d+\}\], MixedUnit\[\{HoursOfRightAscension, MinutesOfRightAscension, SecondsOfRightAscension\}\]\] (regex)
Sunrise, Sunset & DaylightQ¶
$ wo 'Sunrise[GeoPosition[{52.52, 13.405}], DateObject[{2024, 6, 21}]]'
DateObject\[\{2024, 6, 21, 2, 4[23], \d+\.\d+\}, Instant, Gregorian, 0\.\] (regex)
$ wo 'Sunset[GeoPosition[{52.52, 13.405}], DateObject[{2024, 6, 21}]]'
DateObject\[\{2024, 6, 21, 19, 33, \d+\.\d+\}, Instant, Gregorian, 0\.\] (regex)
SolarEclipse & LunarEclipse¶
The next eclipse after a date — its time of greatest eclipse or its type: