Ephemeris
Ruby Class::Ephemeris
This is a complete ephemeris class for Ruby. The code can easily be used in other languages or wrapped for use as a CLI application or on a web page.
The system is an implementation of this in-depth description and with Jean Meeus' "Astronomical Formulae for Calculators" as reference. The basic data from the in-depth description has been tweaked somewhat to better fit our era.
Version 1.2.0 - Improved Accuracy
This version includes significant accuracy improvements:
- Updated obliquity of ecliptic to IAU 2006 standard (23.439279444°) with proper time-dependent formula
- Implemented higher-precision planetary mean motion values for all planets
- Enhanced calculations now use research-validated constants from JPL ephemeris data
- Better long-term accuracy especially for dates far from J2000.0 epoch
Usage is simple and straightforward:
o = Ephemeris.new(date, lat, lon, tz)
...creates a new ephemeris object for the "date" (a string in ISO format 2020-12-16)
by supplying the observer's latitude (lat), longitude (lon) and time zone (tz).
Example: today = Ephemeris.new("2020-12-16", 59.568, 10.02, 1)
You will then have access to the following data:
today.sun
today.moon
today.mercury
today.venus
today.mars
today.jupiter
today.saturn
today.uranus
today.neptune
By calling any of these, you will get back an array with the following data:
[ra, dec, distance, ra_string, dec_string, rise, transit, set]
where:
ra = object's Right Ascension (float)
dec = object's Declination (float)
distance = object's distance from Earth in AUs (float) - except for the Moon
ra_string = ra in a presentable string, e.g "17h 24m 31s"
dec_string = dec in a presentable string, e.g "-24° 16´ 47˝"
rise = object's time of rise above the horizon (float, fraction of 24h)
transit = object's time of transit (float, fraction of 24h)
set = object's time of setting (float, fraction of 24h)
You will also get access to the method "print" that will print out a nice table with data fro the planets:
today.print
Planet │ RA │ Dec │ Dist. │ Rise │ Trans │ Set
────────┼─────────────┼──────────────┼───────┼───────┼───────┼──────
Mercury │ 17h 24m 31s │ -24° 16´ 47˝ │ 1.44 │ 09:27 │ 12:02 │ 14:38
Venus │ 15h 53m 7s │ -18° 57´ 29˝ │ 1.50 │ 06:56 │ 10:31 │ 14:05
Mars │ 1h 16m 21s │ 8° 34´ 10˝ │ 0.75 │ 12:54 │ 19:54 │ 02:54
Jupiter │ 20h 4m 43s │ -20° 49´ 46˝ │ 5.87 │ 11:27 │ 14:42 │ 17:58
Saturn │ 20h 7m 11s │ -20° 35´ 38˝ │ 10.79 │ 11:27 │ 14:45 │ 18:03
Uranus │ 2h 18m 28s │ 13° 20´ 44˝ │ 19.08 │ 13:19 │ 20:56 │ 04:33
Neptune │ 23h 17m 19s │ -5° 45´ 42˝ │ 29.99 │ 12:35 │ 17:55 │ 23:15