R package for calculating sun position, sunlight phases (times for sunrise, sunset, dusk, etc.), moon position, moon rise and set times, and lunar phase for the given location and time.
It is a full R implementation of the JavaScript library SunCalc, vectorized to work on large data. Most calculations are based on the formulas given in the Astronomy Answers articles about position of the sun and the planets.
# from CRAN
install.packages("suncalc")
# development version from GitHub
# install.packages("remotes")
remotes::install_github("datastorm-open/suncalc")| Function | Computes | date |
|---|---|---|
getSunlightTimes() |
sunlight phases (sunrise, sunset, dusk, night, ...) | Date |
getSunlightPosition() |
sun altitude and azimuth | Date, POSIXct or character |
getMoonTimes() |
moon rise and set times | Date |
getMoonPosition() |
moon altitude, azimuth, distance and parallactic angle | Date, POSIXct or character |
getMoonIllumination() |
moon illuminated fraction, phase and angle | Date, POSIXct or character |
All functions return a data.frame, and share the same arguments:
date,lat,lon: one or several dates, for a single location,- or
data: adata.framewith columnsdate,latandlon, for several locations, keep: the variables to return (all by default),tz(getSunlightTimes()andgetMoonTimes()): time zone of the results ("UTC"by default).
library(suncalc)
getSunlightTimes(date = as.Date("2026-06-21"), lat = 48.86, lon = 2.35, tz = "Europe/Paris",
keep = c("sunrise", "solarNoon", "sunset", "night"))
# date lat lon sunrise solarNoon sunset night
# 1 2026-06-21 48.86 2.35 2026-06-21 05:48:09 2026-06-21 13:53:35 2026-06-21 21:59:01 <NA>
# several locations
data <- data.frame(date = as.Date(c("2026-06-21", "2026-12-21")),
lat = c(48.86, 69.65),
lon = c(2.35, 18.96))
getSunlightTimes(data = data, keep = c("sunrise", "sunset", "night"), tz = "Europe/Paris")
# date lat lon sunrise sunset night
# 1 2026-06-21 48.86 2.35 2026-06-21 05:48:09 2026-06-21 21:59:01 <NA>
# 2 2026-12-21 69.65 18.96 <NA> <NA> 2026-12-21 16:57:10
getMoonTimes(date = as.Date("2026-06-21"), lat = 48.86, lon = 2.35, tz = "Europe/Paris")
# date lat lon rise set alwaysUp alwaysDown
# 1 2026-06-21 48.86 2.35 2026-06-21 13:20:51 2026-06-21 01:28:57 FALSE FALSE
getSunlightPosition(date = as.POSIXct("2026-06-21 12:00:00", tz = "Europe/Paris"), lat = 48.86, lon = 2.35)
# date lat lon altitude azimuth
# 1 2026-06-21 12:00:00 48.86 2.35 0.9823635 -0.8941455
getMoonIllumination(date = as.Date(c("2026-06-21", "2026-06-29")))
# date fraction phase angle
# 1 2026-06-21 0.3982594 0.2173872 -1.168386
# 2 2026-06-29 0.9894033 0.4671750 -1.940759getSunlightTimes() and getMoonTimes() return, for each requested day, the times of the events occurring that day in tz (from 00:00 to 24:00), whatever the system time zone.
A time is NA when the event doesn't occur that day:
- the sun doesn't reach the corresponding altitude: no
night/nightEndin summer at high latitudes (the sun never goes 18° below the horizon, as in Paris on June 21 above), nosunrise/sunsetduring polar day or polar night (Tromsø on December 21 above), - the moon doesn't rise or set that day (about once a month, as moonrise and moonset are about 50 minutes later each day).
You can read about the different twilight phases in the Twilight article on Wikipedia.
Each variable is a POSIXct in tz:
| Variable | 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) |
altitude: sun altitude above the horizon in radians, e.g.0at the horizon andpi/2at the zenith (straight over your head)azimuth: sun azimuth in radians (direction along the horizon, measured from south to west), e.g.0is south andpi * 3/4is northwest
rise: moonrise time (POSIXctintz)set: moonset time (POSIXctintz)alwaysUp:TRUEif the moon never rises / sets and is always above the horizon during the dayalwaysDown:TRUEif the moon is always below the horizon
altitude: moon altitude above the horizon in radiansazimuth: moon azimuth in radiansdistance: distance to moon in kilometersparallacticAngle: parallactic angle of the moon in radians
fraction: illuminated fraction of the moon; varies from0.0(new moon) to1.0(full moon)phase: moon phase; varies from0.0to1.0, 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 | |
| 1 | New Moon |
By subtracting the parallacticAngle from the angle one can get the zenith angle of the moon's bright limb (anticlockwise).
The zenith angle can be used to draw the moon shape from the observer's perspective (e.g. moon lying on its back).
See NEWS.md for the changes of each version.