I've long been a fan of the great software from Stephen Trainor called The Photographer's Ephemeris. Used on your home computer or laptop you can calculate all sorts of useful information before heading out into the field—things like where and when the sun will set, moonrise locations, and exactly how these events will unfold on any future date. That's great software, but don't forget that we're already living in the future; we need our software live and portable and right now. That's probably why Trainor created his just released version of The Photographer's Ephemeris for the iPhone. Take your tools with you into the field and calculate all that useful information on the spot and on a moment’s notice. Wondering where the moon will rise over that distant hill? Plug in the info and watch your iPhone—and The Photographer's Ephemeris—do the rest.