This module implement some of Jan Meeus' astronomical formulas in Julia.
It was written while I was learning Julia version 0.2 and 0.3, and some of the code looks to have aged poorly, although it runs OK in Julia version 1.0.
A better and more comprehensive library of astronomical routines can be found at JuliaAstro/AstroLib.
using Astro
What was the Right Ascension and Declination of the Moon on Feb 25 1979 at 16h00m UT?
jd = date_to_jd(1979, 2, 26, 16, 0, 0);
geoecl_long, geoecl_lat, rad = moon_dimension3(jd);
ra_rad, dec_rad = ecl_to_equ(geoecl_long, geoecl_lat, obliquity(jd));
ra_deg = ra_rad / 2pi |> fday_to_hms
#-> (22, 33, 29.10833089183143) # RA 22 33 29.1
What phase is the moon on October 31 2014:
jd = date_to_jd(2014, 10, 31, 0, 0, 0);
moon_illuminated_fraction_high(jd)[1]
#-> 0.48777635849493634
What age is it:
#-> 7.302239900906831
What is the current Greenwich Sidereal Time:
apparent_sidereal_time_greenwich(Dates.datetime2julian(now())) |> radianstime_to_fday |> fday_to_hms
#-> (7, 55, 41.038224676074606) or 7:55:41
Where is Mercury at the moment?
println("Right Ascension: ", fday_to_hms(radianstime_to_fday(ra)))
# (8, 53, 12.632065656522173)
println("Declination: ", rad2deg(decl))
# Declination: 14.963269087821232
JPL give Right Ascension: 08h 53m 01.4s and Declination: 15° 12' 04.5"
Jean Meeus, Astronomical Algorithms, second edition, 1998, Willmann-Bell, Inc.