This is a very nice and simple astronomy app which is designed to help amateur enthusiasts. Night Sky Tools gives you useful observational data about earth,moon,sun,solar system stars, comets,etc.
Night Sky Tools is made based on the premise that if people want to observe stars, they probably go somewhere far from city lights and therefor possibly loose cellphone reception and data coverage. That’s why Night Sky Tools is mostly an offline app; meaning most of the information and functions don’t need internet connection at all.
If you want to add to your knowledge of the sky above, Night Sky Tools can help you learn.