What are some alternatives?
When comparing Sky Map of Constellations and Star Chart, you can also consider the following products
NASA App - Showcases a huge collection of the latest NASA content
Stellarium - Stellarium is a free open source planetarium for your computer.
Google Sky Map - Google Sky Map is a free hand-held planetarium that allows you to identify stars, planets and more.
Sky Map - Sky Map (formerly the Google Sky Map) turns your Android-powered mobile phone into a window on the...
KStars - KStars is a Desktop Planetarium for KDE.
Solar System Scope - 3D model of the Solar System and night sky in real time