ruby-sun-times 
Calculates sunrise and sunset times
The algorithm comes from the Almanac for computers.
Usage
Requiring
In a Gemfile/Gemspec:
gem 'ruby-sun-times', require: 'sun_times'Directly:
require 'sun_times'Methods
The two methods rise and set each return a Time.
day = Date.new(2010, 3, 8)
latitude = 43.779
longitude = 11.432
sun_times = SunTimes.new
sun_times.rise(day, latitude, longitude) # => 2010-03-08 05:39:53 UTC
sun_times.set(day, latitude, longitude) # => 2010-03-08 17:11:16 UTCReferences
- http://www.astro.uu.nl/~strous/AA/en/reken/zonpositie.html - Calculations
- http://williams.best.vwh.net/sunrise_sunset_algorithm.htm - Algorithm
- http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/264573 - Ken Bloom's implementation