Sunscreen is a fun, lightweight application that changes your desktop wallpaper based on sunrise and sunset. Simply drag and drop your favorite wallpapers into Sunscreen's preferences, and it'll do the rest.
Sunscreen supports giving five different periods of the day their own wallpaper. You can individually customize the wallpaper that will be used during sunrise, morning, afternoon, sunset, and nighttime.
If you want to skip a period and leave the wallpaper alone, you can simply leave one of those periods empty. For example, if you leave Afternoon empty, the wallpaper for Morning will also be used for Afternoon.
Sunscreen is completely unobtrusive and stays out of your way. It runs solely in your menu bar, leaving your Dock without any extra clutter.
Sunscreen is licensed under The MIT License. You are free to download the source code and build a binary using Xcode. However, if you enjoy using the app, please consider purchasing it on the App Store for a dollar.