Check it out

I've added a new link to the U.S. Naval Observatory (Sunrise-Sunset Data). This website provides a host of astronomical information allowing you to plan your next adventure with a complete knowledge of the amount of daylight and moonlight expectable.

I've used the site several times, most significantly when I was planning the Grand Canyon Rim to Rim to Rim epic. It allowed us to set our start time for 3:30am, knowing not only that it would start getting light at 4:45am and dark at 8:09pm, but that the moon would aid us for a large portion of the night.