Get event start and stop time from the event click in timelineview in fullcalendar

I have created fullcalendar with scheduler. I have created an eventClick like this in it:

eventClick:  function(event, jsEvent, view) {
                var start = event.start;
                var stop = event.end;
                openModal(start, stop);
                }

When I check start and stop, they are nothing but objects. How can I retrieve start and stop dates from here? I was able to get title and other things from here