What is the name of that astronomy app and is it accessible?

I believe the app you are referring to is called sky safari. The second part of your question is more complicated and depends by what you mean by accessible. Given that the app's primary function is to assist users in astronomy, it is amazingly VoiceOver friendly. I honestly wouldn't have faulted this app a bit if it wasn't. I can only imagine that people would be using this while sitting outside in the dark and the amount of light most people need to read would be counterproductive to stargazing. When You open the app, the screen you see does exactly what you describe. It displays an image of what the sky in front of you should look like at tje present moment in time. With VO on, you are not able to manipulate this image at all and if you put you finger on the image, you'll receive no feedback. Now across the bottom is a row of buttons all VO labeled and any content you open is flawlessly accessible to VO. the row of buttons continues to the right so a three finger swipe from right to left will bring the rest of them across the bottom. There is one button called sky week that will tell you some astronomical fact about each night's sky. There is some technical information about degrees and such at the top of the screen that VO will read when you touch it. With VO off, you can zoom in and out and pan all around on the main image of the sky. Honestly I don't have much vision and I don't know a lot about astronomy so this app is too much for me but it is full of detailed information and is very well designed. For someone highly interested in astronomy, this would be a great app.

Sky Safari is a very nice app, probably the most comprehensive one I've seen thus far. I only use it for looking up descriptions of planets, moons, stars, constellations, Messier objects, etc. The main purpose of this app is to help find objects in the night sky and due to the graphical nature of this isn't usable with VO. However, the descriptions go way past what I've seen gathered in other apps and will be a good resource for learning more about astronomy. It's also nice for when you're accompanying someone during a stargazing session and bits of information are needed about a specific object. With regards to what the previous commenter said about it seeming counterproductive while stargazing due to screen glare, this isn't the case. The app uses "red light" in order to preserve night vision. This is similar to using a "red light" torch to illuminate a book or chart while stargazing.