Here are a few suggestions on how some more features can be added to the timeline to make it more useful:
Currently, we are relying on sequential years for some calculations. Design the timeline such that nonsequential years and missing years can be handled (let me give you a hint; use an index).
Along with the slider, implement a date picker that allows the user to select a date and search for matching events for that specific date.
Implement jQuery UI's effects to close the expanded window.