The app calculates rise and set times for sun, moon and the planets of the solar system. It shows the phases of the moon and calculates dusk and dawn.
When do I have to be on my preferred place for taking photographs with morning light?
When does the sun set on my holiday location?
When can I see Mars? Is the moon visible, too?
If you need an answer to these questions, then you need this app. It uses modern algorithms for most accurate results.
On the homepage you can find more information.