I've released ruby-sun-times, which calculates sunrise and sunset times according to date and location.
Project and Installation
The project is hosted on GitHub
The gem is available from Gem Cutter
If you have a recent version of gem, you can install it with
$ gem install ruby-sun-times
Here's how it works:
$ irb >> require 'rubygems' => true >> require 'sun_times' => true >> SunTimes.set(Date.today, 44, 11).localtime => Tue Mar 09 18:14:08 +0100 2010
So, the sun will be setting round here at 6:14 PM local time.