Star Walk 2
If you have the original, there may only be enough to make you buy the sequel. If you’re a serious stargazer. Some of the new content requires an in-app upgrade. Such as the ability to track satellites, more constellation details, and 3-D models of the planets. Each is $0.99, but the best option is to buy all five extras for $2.31. Star Walk 2 ($2.99)
Stellarium Mobile Sky Map
Stellarium Mobile Sky Map ($2.49)
Night Sky Pro
Suppose you need clarification on whether this whole stargazing thing is worth a measly $2.49. In that case, you can check out Night Sky Lite (free) or The Night Sky ($0.99), which stagger the features depending on how much you pay. It’s worth it to go with Night Sky Pro, as it includes the time machine, deep space objects. With other perks not found in the free or cheaper edition. As the new flagship to the family, I expect to see more features and frequent updates to this edition. Night Sky Pro
NASA
NASA (free)
ISS Detector Pro
ISS Detector Pro ($2.75)
Sky Guide
Sky Guide ($2.99)
Night Sky Tools
Night Sky Tools (free)
SkyPortal
SkyPortal (free)
SkEye Astronomy
SkEye Astronomy (free)
Star Tracker
Star Tracker (free)