Astro - astronomy formulas
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 kind of runs OK in Julia version 1.0.
A much better and more comprehensive library of astronomical routines can be found at JuliaAstro/AstroLib.
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 is the current phase of the moon:
jd = Dates.datetime2julian(now()) moon_illuminated_fraction_high(jd) #-> 0.12195292764741428
What age is it:
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
Calculate the apparent position of Venus on 1992 December 20. Apparent RA should be 316.172791 = 21h.078194 = 21h04m41.50. Apparent Declination should be -18.88801 = -18d53m16.8s.
using Astro, Dates jd = Dates.datetime2julian(Dates.DateTime(1992, 12, 20, 0, 0, 0)) ra, decl = geocentric_planet(jd, "Venus", nut_in_lon(jd), obliquity_high(jd) , days_per_second) dayfraction = radianstime_to_fday(ra) println("Right Ascension: ", fday_to_hms(dayfraction)) Right Ascension: (21, 4, 43.468973979426664) println("Declination: ", rad2deg(decl)) Declination: -18.88572837948753
Jean Meeus, Astronomical Algorithms, second edition, 1998, Willmann-Bell, Inc.