If youre a serious astronomer, this is a very good app to have, loaded with tons of features not found in many other astronomy/planetarium apps. Its hard to figure out at first because it doesnt follow the design philosophy of Apple (more like the old days of Palm OS which is where it came from) but once you got it, its very easy to breeze through. Dont buy it if youre a newbie/beginner, it wasnt made for you yet. But when youve gotten good enough at astronomy, come back to this app. You wont believed how much stuff its loaded with. The author is active and have been releasing updates slowly over the years. "Slowly" because there isnt any thing to improve on but fixing bugs and staying current with newer iOS versions, lol. These days, I used this together with Redshift app and that gives me all the astronomy needs from my iPhone. Planets, satellites, comets, sunsets/sunrises, Jupiters moons, Polaris adjustments, etc, etc.