If you can't see the timeline (which shows rise, set, transit, moon phase and twilight events), it's almost certainly because either
- It's been hidden
- Geodetics mode is enabled
You can read how to exit geodetics mode here: How do I exit Geodetics Mode?
To unhide the timeline (assuming you're not in geodetics mode), simply swipe up on the altitude chart, as shown:
You can hide the timeline again by swiping it downwards: