suncalc is a tiny BSD-licensed Common Lisp library for calculating sun position, sunlight phases (times for sunrise, sunset, dusk, etc.), moon position and lunar phase for the given location and time. It is a port of the SunCalc Javascript library (https://github.com/mourner/suncalc), created by Vladimir Agafonkin (@mourner).
// get today's sunlight times for London
(setq times (suncalc:get-times get-universal-time 51.5 -0.1))
// format sunrise time from the Date object
var sunriseStr = times.sunrise.getHours() + ':' + times.sunrise.getMinutes();
// get position of the sun (azimuth and altitude) at today's sunrise
var sunrisePos = SunCalc.getPosition(times.sunrise, 51.5, -0.1);
// get sunrise azimuth in degrees
var sunriseAzimuth = sunrisePos.azimuth * 180 / Math.PI;
SunCalc is available on Ultralisp: (TO BE DONE AFTER TESTING)
(ql:quickload :suncalc)
SunCalc.getTimes(/*Date*/ date, /*Number*/ latitude, /*Number*/ longitude, /*Number (default=0)*/ height)
Returns an object with the following properties (each is a Date
object):
Property | Description |
---|---|
sunrise |
sunrise (top edge of the sun appears on the horizon) |
sunriseEnd |
sunrise ends (bottom edge of the sun touches the horizon) |
goldenHourEnd |
morning golden hour (soft light, best time for photography) ends |
solarNoon |
solar noon (sun is in the highest position) |
goldenHour |
evening golden hour starts |
sunsetStart |
sunset starts (bottom edge of the sun touches the horizon) |
sunset |
sunset (sun disappears below the horizon, evening civil twilight starts) |
dusk |
dusk (evening nautical twilight starts) |
nauticalDusk |
nautical dusk (evening astronomical twilight starts) |
night |
night starts (dark enough for astronomical observations) |
nadir |
nadir (darkest moment of the night, sun is in the lowest position) |
nightEnd |
night ends (morning astronomical twilight starts) |
nauticalDawn |
nautical dawn (morning nautical twilight starts) |
dawn |
dawn (morning nautical twilight ends, morning civil twilight starts) |
SunCalc.addTime(/*Number*/ angleInDegrees, /*String*/ morningName, /*String*/ eveningName)
Adds a custom time when the sun reaches the given angle to results returned by suncalc:get-times
.
The *times*
variable contains all currently defined times.
(suncalc:get-position time-and-date latitude longitude)
Returns an object with the following properties:
altitude
: sun altitude above the horizon in radians, e.g.0
at the horizon andPI/2
at the zenith (straight over your head)azimuth
: sun azimuth in radians (direction along the horizon, measured from south to west), e.g.0
is south andMath.PI * 3/4
is northwest
(suncalc:get-moon-position time-and-date latitude longitude)
Returns an struct with the following properties:
altitude
: moon altitude above the horizon in radiansazimuth
: moon azimuth in radiansdistance
: distance to moon in kilometersparallactic-angle
: parallactic angle of the moon in radians
(suncalc:get-moon-illumination time-and-date)
Returns an object with the following properties:
fraction
: illuminated fraction of the moon; varies from0.0
(new moon) to1.0
(full moon)phase
: moon phase; varies from0.0
to1.0
, described belowangle
: midpoint angle in radians of the illuminated limb of the moon reckoned eastward from the north point of the disk; the moon is waxing if the angle is negative, and waning if positive
Moon phase value should be interpreted like this:
Phase | Name |
---|---|
0 | New Moon |
Waxing Crescent | |
0.25 | First Quarter |
Waxing Gibbous | |
0.5 | Full Moon |
Waning Gibbous | |
0.75 | Last Quarter |
Waning Crescent |
By subtracting the parallactic-angle
from the angle
one can get the zenith angle of the moons bright limb (anticlockwise).
The zenith angle can be used to draw the moon shape from the observers perspective (e.g. moon lying on its back).
(suncalc:get-moon-times date latitude longitude (&optional in-utc))
Returns an object with the following properties:
rise
: moonrise time asDate
set
: moonset time asDate
always-up
:T
if the moon never rises/sets and is always above the horizon during the dayalways-down
:T
if the moon is always below the horizon
By default, it will search for moon rise and set during local user's day (from 0 to 24 hours).
If in-utc
is set to T
, it will instead search the specified date from 0 to 24 UTC hours.