Knowing the time of first light and last light can be important for outdoor adventures.
Surfers want dawn patrol.
Photographers want the “golden hour” just after sunrise and before sunset for good lighting.
Climbers often want to plan a trip around first available light - like hike the approach trail in the dark, but then reach the first part of tricky route finding, crevasses or technical climbing when you can see what you're doing.
There are a few ways to figure this out. For example, at my latitude of about 45° north in Oregon, the sunrise time minus about 30 minutes (and the sunset time plus about 30 minutes) gives a pretty good approximation for first and last light. (Sunrise and sunset are available on just about every basic weather app on your phone.)
But, if you want to get a little fancier, such as figuring out first light at some point in the future for an upcoming trip, or in a different location/latitude, or both, then things get a little trickier.
There are some in-depth websites that show times for civil twilight, nautical twilight, and astronomical twilight, that relate to the number of degrees that the sun is below the horizon, but not many people really know what those technical terms mean. (For our purposes, we're interested in civil twilight, which is pretty much when you can stumble around outside without a headlamp and not fall on your face.)
So, how about a phone app that simply tells you first light, last light, sunrise and sunset, with a nice clean interface and no fluff?
Well, here’s an iPhone app that does this one thing and does it perfectly - Sunrise Times. (Android peeps, you're on your own.)
It tells you sunset, sunrise, first light and last light of anywhere on earth. This is the free version. Pay an extra tree bucks for the paid version, and you get to choose a date in the past or future, helpful for trip planning.
Simple, easy to use, good display. I like it.