The Martian letterboxed (from iTunes). The Siri remote ctrol of the Apple TV has a nifty functi that allows you to switch between mailbox mode and fullscreen mode
Modern HDTV screens have an entire image size of 16 wide by 9 high. It's 1.78: 1. Most of the (ultra) high definiti TV shows you watch cable / satellite / streaming are also mastered in this report. The ctent perfectly matches the physical format of the TV screen.
However, movie films, even before the era of high definiti, were "filmed" with aspect ratios ranging from 1.85: 1 to 2.39: 1. Popular aspect reports have changed over time, but it is a comm range today. For example, Star Wars: The Last Jedi was released at 2.39: 1. The Martian shown above, was released at 2.35: 1.
If you want To know the aspect ratio of a movie, you can usually find out by looking in the internatial database of the movie, imdb.com, under the technical heading …