Who knew a solar calculator could be so handy?

By Martine Powers
Globe Staff

Reviewing: Sunrise
By: Adair Systems
Available on: iPhone
Price: 99 cents
Should you get it? Yes, if sunlight is kind of your thing.

The "Sunrise" app is so bare-basics, it feels like it should come pre-uploaded on every iPhone, a la "Weather" and "Stocks."

It's been a staple on my iPhone for years, but I was flummoxed when a co-worker - brooding about daylight savings - announced that she'd never even heard of the app, which functions as a solar calculator.

The concept is simple: "Sunrise" uses your GPS coordinates (or one of hundreds of pre-uploaded locations worldwide) to determine the exact moment of sunrise and sunset at your spot, as well as moonrise and the end of twilight.

Since I downloaded this almost-freebie, I use it way more often than I ever anticipated. Will you have time for a post-work run before it gets too dark? Trying to time your lighthouse visit to coincide with a romantic sunset? Planning a road trip and want to hit the road before dawn? This app has answers.

And there are a few features other than sunrise and sunset: Data on lunar phases helps plan when to go on that moonlit walk. And I'm not really sure I ever cared to know when "solar noon" takes place, but it's a fun fact to have handy!

"Sunrise" is particularly helpful for travel or hiking. If you choose one of hundreds of pre-loaded locations around the globe (rather than your real-time GPS location) the app has saved a database of solar data for years to come. That way, even if you're in a place with 3G or wi-fi access (think: a remote Caribbean island or the wilds of the Berkshires) you can still get the stats to maximize your daytime.

Of course, if you download the app, you'll discover that - surprise! - the recent "fall back" in daylight savings time means the sun now sets at 4:35 p.m. Which is kind of depressing. Seriously.

But at least you'll know that solar noon takes place at 11:29 a.m.!