A new version of R will be released on 2019-04-26. One significant change is the support of HCL colour definitios and palettes. Some defaults for colour palettes are changing (for the better) but small differences may visible in how plots look compared to earlier R versions. There is a post with a summary at the R blog, and a paper arXiv:1903.0649 describing why better palettes for data plotting can be defined.
Another significant change is that serialization format 3 becomes the default. As this format can be read only by R (>= 3.5.0) when sharing files created with save() or saveRDS(), and when sharing saved workspaces one needs to make sure the recipient is using a recent version of R or override this new default to create the files to be shared using the older serialization format 2.
All the packages I maintain should work correctly under R (= 3.6.0), but if you discover a problem, please, raise an issue at bitbucket within the repository of the affected package.
As far as I know there are in CRAN four R packages implementing the computations for the position of the sun and times of sunrise and sunset: ‘photobiology’, ‘fishmethods’, ‘solartime’ and ‘suncalc’.
The functions sun_angles() and day_night() from package ‘photobiology’ use Meeus equations as used by NOAA Solar Calculator https://www.esrl.noaa.gov/gmd/grad/solcalc/ which could be more precise than those in NOAA’s Excel worksheet which implement a simplified version of the Meeus equations especially for far into the past or far into the future calculations. The approximations based on Meuus equations are very good for years between 1800 and 2100 and results should still be sufficiently accurate for the range from -1000 to 3000 as long as the computation of Julian dates is correct. The Excel implementation is only valid for dates between 1901 and 2099 because of how Julian dates are computed in Excell.
Function astrocalc4r() from package ‘fishmethods’ also implements Meeus equations (the authors work at NOAA). Function computeSunPosition() from package ‘solartime’ uses unspecified equations and function getSunlightPosition() is an R interface to the ‘suncalc.js’ library, part of the ‘SunCalc.net’ project <http://suncalc.net>.
Function computeSunPosition() from package ‘solartime’ uses unspecified equations and function getSunlightPosition() is an R interface to the ‘suncalc.js’ library, part of the ‘SunCalc.net’ project <http://suncalc.net>.